
Qass_ 
Book- 



CHEMISTRY 



IN ITS APPLICATION TO 

AGEICULTUEE AND PHYSIOLOGY. 

BY 

JUSTUS LIEBIG, M.D., Ph.D., F.R.S., M.R.I.A., 

PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OP GIESSEN, 
ETC., ETC., ETC. 

EDITED FROM THE MANUSCRIPT OF THE AUTHOR 

By LYON PLAYFAIR, Ph. D. 

WITH 

VERY NUMEROUS ADDITIONS, AND A NEW CHAPTER ON SOILS. 



FOURTH AMERICAN, FROM THE SECOND ENGLISH EDITION, 
WITH 

NOTES, AND APPENDIX, 

BY 

JOHN Wi WEBSTER, M. D., 

ERVING PROFESSOR OP CHEMISTRY IN HARVARD UNIVERSITY. 



CAMBRIDGE: 
PUBLISHED BY JOHN OWEN. 

BOSTON, JAMES MUNROE AND COMPANY, AND CHARLES C. LITTLE AND JAMES BROWN; 

NEW YORK, WILEY AND PUTNAM, AND GEORGE C. THORBURN ; PHILADELPHIA, 

THOMAS, COWPERTHWAIT, AND COMPANY, AND CAEEY AND HART; 

BALTIMORE, CUSHINO AND BROTHER. 

1843. 



^ 






Entered according to Act of Congress, in the year 1842, by 

John Owen, 

in the Clerk's office of the District Court of the District of Massachusetts. 






C A :.I B k I D G E ; 

STEREOTYPED ^AN"D PRINTED BY 

MET CALF, KEITH, AND NICHOLS, 

PRINTEISS TO THE CNIVEESITY. 



CONTENTS. 



Preface to the Third American Edition 

Dedication 

Preface to the Second English Edition 

Object of the Work 



PAG a 

V 

Xlll 

XVII 

21 



PART FIRST. 

ON THE CHEMICAL PROCESSES IN THE NUTRITION OF VEGETABLES. 

CHAPTER PAGE 

I. — On the Constituent Elements of Plants . . 24 

n. — On the Assimilation of Carbon . . .30 

III. — On the Origin and Action of Humus . . 63 

IV. — On the Assimilation of Hydrogen . . .80 

V. — On the Origin and Assimilation of Nitrogen . 85 

VI. — On the Inorganic Constituents of Plants . . 105 

Vn. — The Art of Culture . . . . 126 

Vni. — On the Alternation (Rotation) of Crops . . 161 

IX. — On Manure ..... 174 

Supplementary Chapter. — On the Chemical Constitu- 
ents of Soils ..... 208 

Appendix to Part I. ..... 249 

Action of Charcoal on Vegetation . . 249 

Mode of Manuring Vines .... 253 

Root Secretions ..... 256 

Peat Compost ..... 258 

Source of the Carbon of Plants . . . 260 

Source of the Hydrogen of Plants . . . 263 
Dependence of the Nutritive Qualities of Plants on 

Nitrogen . . . . .265 



iv CONTENTS. 

Difference in the Power of Plants to decompose 

Ammonia ..... 266 

Practical Inferences .... 268 

Use of Phosphate of Soda . . . .286 

Daniell's Artificial Manure . . . 287 



PART SECOND. 

ON THE CHEMICAL PROCESSES OF FERMENTATION, DECAY, AND 
PUTREFACTION. 

CHAPTER * PAGE 

I. — Chemical Transformations . . . 289 
n. — On the Causes which effect Fermentation, Decay, 

and Putrefaction .... 292 
m. — Fermentation and Putrefaction . . . 300 
IV. — On the Transformation of Bodies which do not con- 
tain Nitrogen as a constituent, and of those in 
which it is present .... 305 
V. — Fermentation of Sugar .... 313 
VI. — Eremacausis, or Decay , . . 322 
Vn. — Eremacausis of Bodies destitute of Nitrogen : For- 
mation of Acetic Acid . . . 329 
VIII. — Eremacausis of Substances containing Nitrogen: 

Nitrification . . . .334 

IX. — On Vinous Fermentation : Wine and Beer . 338 

X. — On the Decay of Woody Fibre . . 357 

XL — On Vegetable Mould . . . .363 

Xn. — On the Mouldering of Bodies : Paper, Brown Coal, 

and Mineral Coal . . . .365 

Xni. — On Poisons, Contagions, and Miasms . 373 

Appendix to Part II. . . . . . 415 



Tables, — Showing the Proportion between the Hessian 

and English Standard of Weights and Measures 416 
Index ...... 419 



PEEEACE 



THIRD AMERICAN EDITION. 



This volume constitutes the First Part of Professor 
Liebig's Report on Organic Chemistry, drawn up by 
request of the British Association for the Advancement 
of Science.* 

The interest excited in Great Britain on the appear- 
ance of this work from one of the most eminent 
chemists in Europe, and the high encomiums be- 
stowed upon it by individuals, and learned bodies, 
together with the various notices of it which have 
been published by Professor Lindley, Professor Dau- 
beny, and others, all concurring in the opinion, that 
the information it contains is of great amount, and 
that from its publication might be dated a new era 

* The Second Part has just been published, viz., "Animal Chemistry, 
or Organic Chemistry in its Application to Physiology and Pathology. 
By Justus Liebig, M. D., F. R. S., M. R. I. A., Professor of Chemistry 
in the University of Giessen, &c., &-c., &c. Edited from the Author's 
Manuscript, by William Gregory, M. D., F. R. S., M. R. I. A., 
Professor of Medicine and Chemistry in the University and King's 
College, Aberdeen. With Additions, Notes, and Corrections, by Dr. 
Gregory, and others by John W. Webster, M. D., Erving Professor of 
Chemistry in Harvard University." 



Vi PREFACE TO THE 

in the art of agriculture, induced the editor to suggest 
its republication in this country. 

Contrary to the expectations of the author, and of 
the editor, the work has received the attention not 
only of scientific readers, for whom it was written, 
but of practical agriculturists, and those who could 
hardly have been supposed prepared to derive much 
advantage from its perusal. The influence of the 
opinions of Professor Liebig, and the impetus the 
appearance of the present work gave to the advance- 
ment of scientific agriculture, have been e,vinced by the 
many publications which have since appeared, both in 
Great Britain and in this country. 

What is valuable in too many of these publications, 
diluted as it has been and mingled with erroneous 
statements, was for the first time given in a consistent 
shape in the present work. 

Although the fact that nitrogen is essential to the 
nutrition of plants was known before the publication 
of Professor Liebig's work, and it had, indeed, been 
ascertained by Saussure, that germinating seeds absorb 
nitrogen, it was not supposed that it is derived from 
the atmosphere exclusively. And this has been 
deemed the chief discovery of the author, so far as 
practical questions are concerned. It had indeed been 
suspected, that very small quantities of ammonia in 
the atmosphere might furnish the nitrogen, ammonia 
being a compound of nitrogen and hydrogen. It 
may be objected, that the quantity of ammonia pres- 
ent in the atmosphere, and in rain and snow water, is 



THIRD AMERICAN EDITION. Vll 

exceedingly small, quite insufficient for the supply of 
all the nitrogen that enters into the vegetable struc- 
ture. To this it has been replied by Professor Lind- 
ley, in an elaborate review of Liebig's work, that 
" the quantity of ammonia given off from thousands 
of millions of putrefying animals must furnish an 
abundant, an everlasting source of that principle." 

Important as ammonia, or its nitrogen, is conceived 
to be to plants, it will be seen that Liebig considers 
carbon not less so. 

Since the appearance of the former editions of this 
work, the opinions of American chemists in regard to 
humus, have become so generally diffused, in the 
various Agricultural Keports, that it has not been 
deemed necessary to retain, in this edition, much that 
was appended to the second. 

Professor Lindley, in speaking of humus, recogni- 
ses it as " the dark substance which remains when 
manure is thoroughly rotted, and which colors the 
soil black, and without going into any technical ex- 
amination of this product, we may state," he con- 
tinues, "that it is a substance formed by the decay of 
plants, and very rich in carbon." He then quotes the 
expression of Liebig, that this substance, in the form 
in which it exists in the soil, does not yield nourish- 
ment to plants, and expresses surprise, that the author 
should have thought it worth his while to raise such 
a phantom for the mere pleasure of subduing it, for 
no one in Great Britain now entertains the opinion, 
that humus is in itself the food of plants. '^ Every 



Viil PREFACE TO THE 

Student of botany is taught, that humus becomes the 
food of plants only by combining with the oxygen of 
the atmosphere and forming carbonic acid gas, and 
hence the great importance of preserving the roots of 
plants in communication with the atmosphere, which 
is the great source of oxygen." 

In noticing the effect of alkalies, Professor Lindley 
remarks, that it will lead to the explanation of many 
things that were inexplicable before. " When it is 
said, that a plant becomes tired of a soil, and we find 
that manuring fails to invigorate it, the destruction of 
alkalies in the soil, and the want of a sufficient supply 
of those bases in the manure, seem to offer a solution 
of the enigma. And in like manner the gradual de- 
cay of trees in public squares and promenades, where 
the soil is incessantly robbed of alkaline matter for 
the sake of neatness, may probably be ascribed to the 
same cause. So also the injurious action of weeds is 
explained, by their robbing the soil of that particular 
kind of food which is necessary to the crops among 
which they grow. Each will partake of the compo- 
nent parts of the soil, and in proportion to the vigor 
of their growth, that of the crop must decrease ; for 
what one receives the others are deprived of" 

''It is impossible for any one acquainted with gar- 
dening not to perceive the immense importance of 
these considerations, which show, that by adopting 
the modern notion, that the action of soil is chiefly 
mechanical, the science of horticulture has been car- 
ried backwards, instead of being advanced ; and that 



THIRD AMERICAN EDITION. IX 

the most careful examination of the chemical nature 
both of the soil in which a given plant grows, and of 
the plant itself, must be the foundation of all exact 
and economical methods of cultivation." 

Of the importance of alkalies and salts to plants, 
there would seem to be no doubt, and although the 
credit of this discovery is in England given to Liebig, 
it was not new in the United States, having been an- 
nounced by Dr. S. L. Dana of Lowell, and urged 
upon the attention of cultivators in the various Re- 
ports on the Agriculture of Massachusetts, several 
years ago. 

As in this work many chemical and technical terms 
are necessarily made use of, and it may come into the 
hands of some persons who are not familiar with them, 
explanatory notes have been added which it is hoped 
may render the text more intelligible. The notes 
that are contained in the original work are distin- 
guished by initials or abbreviations. 

A valuable addition has been made in the extracts 
from the lectures delivered after the appearance of 
Liebig's work by Professor Daubeny at Oxford, on 
Agriculture and Rural Economy. The greater part 
of the third lecture is given in the Appendix, being 
a summary of the practical applications of the prin- 
ciples developed and discussed in the body of this 
work. 

It has been highly gratifying to the editor, to learn 
from the gentleman under whose supervision the work 
first appeared in England, that its republication, and 



X PREFACE TO THE 

the manner in which it has been edited in this coun- 
try, have met with his entire approbation. To Dr. 
Playfair the editor is also indebted for some valuable 
suggestions which were followed in preparing the 
second edition, and for which he would express his 
thanks. 

A copious index, in which the original work is de- 
ficient, has been added, and numerous errors of the 
English press have been corrected. 

The estimation in which Professor Liebig's work 
was viewed by the "British Association for the Ad- 
vancement of Science," before whom it was brought 
as a Report, has been expressed by Professor Gregory, 
of King's College, in the remark, " that the Association 
had just reason to be proud of such a work, as origi- 
nating in their recommendation." 

On the 30th of November, 1840, at the anniversary 
meeting of the Royal Society, one of the Copley 
medals was awarded to the author ; and on this occa- 
sion, in his absence, the President, the Marquis of 
Northampton, addressed his representative, Professor 
Daniell, as follows. 

" Professor Daniell, I hold in my hand, and deliver 
to you one of the Copley medals, which has been 
awarded by us to Professor Liebig. My principal 
difficulty, in the present exercise of this the most 
agreeable part of my official duty, is to know wheth- 
er to consider M. Liebig's inquiries as most important 
in a chemical or in a physiological light. However 
that may be, he has a double claim on the scientific 



THIRD AMERICAN EDITION. XI 

world, enhanced by the practical and useful ends to 
which he has turned his discoveries." 

To Dr. S, L. Dana, of Lowell, the editor would ac- 
knowledge his obligations for valuable suggestions 
and the communication of some important additions, 
and also to Mr. Charles E. Buckingham, of the Medical 
School of this University, for his valuable assistance 
in correcting the proofs. 

J. W. W. 

Cambridge, September, 1842. 



TO 



THE BRITISH ASSOCIATION 



ADVANCEMENT OF SCIENCE. 



One of the most remarkable features of modern 
times is the combination of large numbers of indi- 
viduals representing the whole intelligence of nations, 
for the express purpose of advancing science by their 
united efforts, of learning its progress, and of commu- 
nicating new discoveries. The formation of such as- 
sociations is, in itself, an evidence that they were 
needed. 

It is not every one who is called by his situation 
in life to assist in extending the bounds of science ; 
but all mankind have a claim to the blessings and 
benefits which accrue from its earnest cultivation. 
The foundation of scientific institutions is an ac- 
knowledgment of these benefits, and this acknowl- 
edgment, proceeding from whole nations, may be 
considered as the triumph of mind over empiricism. 

Innumerable are the aids afforded to the means of 
life, to manufactures and to commerce, by the truths 
b 



XIV DEDICATION. 

which assiduous and active inquirers have discovered 
and rendered capable of practical application. But it 
is not the mere practical utility of these truths which 
is of importance. Their influence upon mental cul- 
ture is most beneficial ; and the new views acquired 
by the knowledge of them enable the mind to recog- 
nise, in the phenomena of nature, proofs of an Infinite 
Wisdom, for the unfathomable profundity of which, 
language has no expression. 

At one of the meetings of the chemical section of 
the " British Association for the Advancement of 
Science," the honorable task of preparing a Report 
upon the state of Organic Chemistry was imposed 
upon me. In the present work I present to the As- 
sociation a part of this Report. 

I have endeavored to develop, in a manner corre- 
spondent to the present state of science, the fundamen- 
tal principles of Chemistry in general, and the laws 
of Organic Chemistry in particular, in their applica- 
tions to Agriculture and Physiology ; to the causes of 
fermentation, decay, and putrefaction ; to the vinous 
and acetous fermentations, and to nitrification. The 
conversion of woody fibre into wood and mineral coal, 
the nature of poisons, contagions, and miasms, and 
the causes of their action on the living organism, have 
been elucidated in their chemical relations. 

I shall be happy if I succeed in attracting the at- 
tention of men of science to subjects which so well 
merit to engage their talents and energies. Perfect 
Agriculture is the true foundation of all trade and in- 



DEDICATION. XV 



dustiy, — it is the foundation of the riches of states. 
But a rational system of Agriculture cannot be formed 
without the application of scientific principles ; for 
such a system must be based on an exact acquaintance 
with the means of nutrition of vegetables, and with 
the influence of soils and action of manure upon them. 
This knowledge we must seek from chemistry, which 
teaches the mode of investigating the composition and 
of studying the characters of the different substances 
from which plants derive their nourishment. 

The chemical forces play a part in all the processes 
of the living animal organism ; and a number of trans- 
formations and changes in the living body are exclu- 
sively dependent on their influence. The diseases in- 
cident to the period of growth of man, contagion and 
contagious matters, have their analogues in many 
chemical processes. The investigation of the chemi- 
cal connexion subsisting between those actions pro- 
ceeding in the living body, and the transformations 
presented by chemical compounds, has also been a 
subject of my inquiries. A perfect exhaustion of this 
subject, so highly important to medicine, cannot be 
expected without the cooperation of physiologists. 
Hence I have merely brought forward the purely 
chemical part of the inquiry, and hope to attract at- 
tention to the subject. 

Since the time of the immortal author of the " Ag- 
ricultural Chemistry," no chemist has occupied him- 
self in studying the applications of chemical principles 
to the growth of vegetables, and to organic processes. 



Xvi DEDICATION. 

I have endeavored to follow the path marked out by 
Sir Humphry Davy, who based his conclusions only 
on that which was capable of inquiry and proof. 
This is the path of true philosophical inquiry, which 
promises to lead us to truth, — the proper object of 
our research. 

In presenting this Report to the British Association 
I feel myself bound to convey my sincere thanks to 
Dr. Lyon Playfair, of St. Andrew's, for the active as- 
sistance which has been aiforded me in its preparation 
by that intelligent young chemist during his residence 
in Giessen. I cannot suppress the wish, that he may 
succeed in being as useful, by his profound and well- 
grounded knowledge of chemistry, as his talents 

promise. 

JUSTUS LIEBIG. 

Giessen, September 1, 1840. 



EDITOR'S PHEFACE 



THE SECOND ENGLISH EDITION, 



The former edition of this work was prepared in 
the form of a Report on the present state of Organic 
Chemistry. The state of a science such as this 
could not be exhibited by a systematic treatise on 
organic compounds, but by showing, that the science 
was so far advanced as to be useful in its practical 
applications. 

The work was written by a Chemist, and address- 
ed to Chemists. The author did not flatter himself, 
that his opinions would be so eagerly embraced by 
agriculturists, as circumstances have shown to be the 
case. Hence his language and style were less adapt- 
ed for them than for those who are conversant with 
the abstract details of chemical science. But the 
eager reception of the work by agriculturists has 
shown, that they possess an ardent desire to profit 
by the aids offered to them by Chemistry. It, there- 
fore, became necessary to adapt the work for those 
who have not had an opportunity of making that 
science a peculiar object of study. 
6* 



Xviii EDITOR'S PREFACE TO THE 

The Editor has endeavored to effect this change. 
In doing so, it was necessary to retain the original 
character of the work ; hence those alterations only 
have been made which are calculated to render the 
work more generally useful. It must be remember- 
ed, that the object of the author was not to write a 
" System of Agricultural Chemistry," but to furnish 
a '' Treatise on the Chemistry of Agriculture." It 
is to be hoped, that those who are acquainted with 
the general doctrines of Chemistry will find no diffi- 
culty in comprehending any of the principles here 
developed. 

The author has enriched the present edition with 
many valuable additions ; allusion may be particular- 
ly made to the practical illustration of his principles 
furnished in the supplementary Chapter on Soils. 
The analyses of soils contained in that chapter will 
serve to point out the culpable negligence exhibited 
in the examination of English soils. Even in the 
analyses of professional chemists, published in detail, 
and with every affectation of accuracy, the estima- 
tion of the most important ingredients is neglected. 
How rarely do we find phosphoric acid amongst the 
products of their analyses ? potash and soda would 
appear to be absent from all soils in the British ter- 
ritories ! Yet these are invariable constituents of 
fertile soils, and are conditions indispensable to their 
fertility. 

It is necessary to state, that all additions and alter- 
ations, with a few unimportant exceptions, have been 



SECOND ENGUSH EDITION. XIX 

submitted to the revision of the author. The Index 
at the end of the volume has been principally com- 
piled from one furnished by Professor Webster, of 
Harvard University, in his American edition of this 
work. The editor gladly avails himself of this op- 
portunity to thank this gentleman for the care and 
attention which he has displayed in superintending 
its republication. 

Primrose, November 22, 1841. 



OEGANIC CHEMISTEY 



IN ITS APPLICATION TO 



VEGETABLE PHYSIOLOGY AND AGKICULTURE. 



The object of Chemistry is to examine into the 
composition of the numerous modifications of mat- 
ter, which occur in the organic and inorganic king- 
doms of nature, and to investigate the laws by 
which the combination and decomposition of their 
parts is effected. 

Although material substances assume a vast vari- 
ety of forms, yet chemists have not been able to de- 
tect more than fifty-five bodies which are simple, or 
contain only one kind of matter, and from these all 
other substances are produced. They are considered 
simple only because it has not been proved that they 
consist of two or more parts. The greater number 
of the elements occur in the inorganic kingdom. 
Four only are found in organic matter. 

But it is evident that this limit to their number 
must render it more difficult to ascertain the precise 
circumstances, under which their union is effected, 
and the laws which regulate their combinations. 
Hence chemists have only lately turned their atten- 
tion to the study of the nature of bodies generated 
by organized beings. A few years have, however, 
sufficed to throw much light upon this interesting 
department of science, and numerous facts have been 
discovered which cannot fail to be of importance in 
their practical applications. 



22 CONDITIONS ESSENTIAL TO NUTRITION. 

The peculiar object of organic chemistry * is to 
discover the chemical conditions essential to the life 
and perfect development of animals and vegetables, 
and generally to investigate all those processes of 
organic nature which are due to the operation of 
chemical laws. Now, the continued existence of all 
living beings is dependent on the reception by them 
of certain substances, which are applied to the nu- 
trition of their frame. An inquiry, therefore, into 
the conditions on which the life and growth of living 
beings depend, involves the study of those substan- 
ces which serve them as nutriment, as well as the 
investigation of the sources whence these substances 
are derived, and the changes which they undergo in 
the process of assimilation. 

A beautiful connexion subsists between the or- 
ganic and inorganic kingdoms of nature. Inorganic 
matter affords food to plants, and they, on the other 
hand, yield the means of subsistence to animals. 
The conditions necessary for animal and vegetable 
nutrition are essentially different. An animal re- 
quires for its development, and for the sustenance 
of its vital functions, a certain class of substances 
which can only be generated by organic beings pos- 
sessed of life. Although many animals are entirely 
carnivorous, yet their primary nutriment must be 
derived from plants ; for the animals upon which 
they subsist receive their nourishment from vegeta- 
ble matter. But plants find new nutritive material 
only in inorganic substances. Hence one great end 
of vegetable life is to generate matter adapted for 
the nutrition of animals out of inorganic substances, 
which are not fitted for this purpose. Now the pur- 

* Every vegetable and animal constitutes a machine of greater or 
less complexity, composed of a variety of parts dependent on each 
other, and acting all of them to produce a certain end. Vegetables and 
anim&,ls, on this account, are called organized beings ; and the chemi- 
cal history of those compounds which are of animal or vegetable origin, 
or of organic substances, is called organic cliemistrij. See Thomson's 
Chemistry of Organic Bodies, and Webster's Manual of Chemistry, 3d 
edit., p. 3G2. 



SUBJECT OF THE WORK. 23 

port of this work is, to elucidate the chemical pro- 
cesses engaged in the nutrition of vegetables. 

The first part of it will be devoted to the exam- 
ination of the matters which supply the nutriment 
of plants, and of the changes which these matters 
undergo in the living organism. The chemical com- 
pounds which afford to plants their principal con- 
stituents, viz. carbon and nitrogen, will here come 
under consideration, as well as the relations in which 
the vital functions of vegetables stand to those of the 
animal economy and to other phenomena of nature. 

The second part of the work will treat of the 
chemical processes which effect the complete de- 
struction of plants and animals after death, such as 
the peculiar modes of decomposition, usually de- 
scribed diS fei'inentation, putrefaction, and decay ; and 
in this part the changes which organic substances 
undergo in their conversion into inorganic com- 
pounds, as well as the causes which determine these 
changes, will become matter of inquiry. 



PART I. 

OF THE CHEMICAL PROCESSES IN THE NUTRITION 
OF VEGETABLES. 



CHAPTER I. 

OF THE CONSTITUENT ELEMENTS OF PLANTS. 

The ultimate constituents of plants are those which 
form organic matter in general, namely, Carbon, Hy- 
drogen, Nitrogen, and Oxygen. These elements are 
always present in plants, and produce by their union 
the various proximate principles of which they con- 
sist. It is, therefore, necessary, to be acquainted 
with their individual characters, for it is only by a 
correct appreciation of these that we are enabled to 
explain the functions which they perform in the veg- 
etable organization. 

Carbon is an elementary substance, endowed with 
a considerable range of affinity. With oxygen it 
unites in two proportions, forming the gaseous com- 
pounds known under the names of carbonic acid and 
carbonic oxide. The former of these is emitted in 
immense quantities from many volcanoes and mineral 
springs, and is a product of the combustion and de- 
cay of organic matter. It is subject to be decom- 
posed by various agencies, and its elements then ar- 
range themselves into new combinations. Carbon is 
familiarly known as chaj^coal, but in this state it is 
mixed with several earthy bodies ; in a state of ab- 
solute purity it constitutes the diamond.* 

* Wood charcoal contains about l-50th of its weigiit of alkaline and 
earthy salts, which constitute the ashes when it is burned. 



OF THE CONSTITUENT ELEMENTS OF PLANTS. 25 

Hydrogen (htflamniable Air) is a very important 
constituent of vegetable matter. It possesses a 
special affinity for oxygen, with which it unites and 
forms water. The whole of the phenomena of decay 
depend upon the exercise of this affinity, and many 
of the processes engaged in the nutrition of plants 
originate in the attempt to gratify it. Hydrogen, 
when in the state of a gas, is very combustible, and 
the lightest body known ; but it is never found in 
nature in an isolated condition. Water is the most 
common combination in which it is presented ; and 
it may be removed by various processes from the 
oxygen, with which it is united in this body. 

Nitrogen * is quite opposed in its chemical char- 
acters to the two bodies now described. Its princi- 
pal characteristic is an indifference to all other sub- 
stances, and an apparent reluctance to enter into 
combination with them. When forced by peculiar 
circumstances to do so, it seems to remain in the 
combination by a vis inei^tice ; and very slight forces 
effect the disunion of these feeble compounds. 

Yet nitrogen is an invariable constituent of plants, 
and during their life is subject to the control of the 
vital powers. But when the mysterious principle of 

* This gas was discovered in 1772, and is called also aiote or azotic 
gas, from the Greek, expressive of its being incapable of supporting 
life. The name JYitrogen was given to it from its entering into the 
composition of nitric acid (aqua fortis). It has been suspected to be a 
compound, but this has not been verified. The atmosphere is compos- 
ed of four fifths nitrogen and one fifth oxygen, not, however, chemical- 
ly united ; it also contains a ten thousandth part of carbonic acid and 
watery vapor. A mixture of oxygen and nitrogen in the proportions 
named, exhibits the general properties of the atmosphere. Nitrogen 
may be obtained from common air by removing its oxygen, and from 
the lean part of flesh meat by boiling it in diluted nitric acid. It unites 
with different proportions of oxygen, and forms as many distinct com- 
pounds, viz. 

form 5 P^o^^o^i'^^ of Nitrogen, nitrous 
^ oxide, or exhilarating gas. 
Binoxide of Nitrogen 

or Nitric oxide. 
Hyponitrous acid. 
Nitrous acid. 
Nitric acid. 
For other details, see Webster's Cliemistnj,dd edit., p. 134, &c. 

3 



JVitrog. 
100 


+ 


Oxyg. 
50 


lOO 


+ 


100 


100 

100 

ino 


+ 

+ 

+ 


150 

200 
250 



26 OF THE CONSTITUENT ELEMENTS OF PLANTS. 

life has ceased to exercise its influence, this element 
resumes its chemical character, and materially assists 
in promoting the decay of vegetable matter, by es- 
caping from the compounds of which it formed a 
constituent. 

Oxygen, the only remaining constituent of organic 
matter, is a gaseous element, which plays a most 
important part in the economy of nature. It is the 
agent employed in effecting the union and disunion 
of a vas-t number of compounds. It is superior to 
all other elements in the extensive range of its af- 
finities. The phenomena of combustion and decay 
are examples of the exercise of its power. 

Oxygen is the most generally diffused element on 
the surface of the earth; for, besides constituting 
the principal part of the atmosphere which surrounds 
it, it is a component of almost all the earths and 
minerals found on its surface. In an isolated state 
it is a gaseous body, possessed of neither taste nor 
smell. It is slightly soluble in water, and hence is 
usually found dissolved in rain and snow, as well as 
in the water of running streams. 

Such are the principal characters of the elements 
which constitute organic matter ; but it remains for 
us to consider in what form they are united in plants. 

The substances which constitute the principal mass 
of every vegetable are compounds of carbon with ox- 
ygen and hydrogen, in the proper relative propor- 
tions for forming water. Woody fibre, starch, sugar, 
and gum, for example, are such compounds of carbon 
with the elements of water. In another class of sub- 
stances containing carbon as an element, oxygen and 
hydrogen are again present ; but the proportion of 
oxygen is greater than would be required for produc- 
ing water by union with the hydrogen. The numer- 
ous organic acids met with in plants belong, with 
few exceptions, to this class. 

A third class of vegetable compounds contains car- 
bon and hydrogen, but no oxygen, or less of that 
element than would be required to convert all the 



OF THE COMPOSITION OF THE ATMOSPHERE. 27 

hydrogen into water. These may be regarded as 
compounds of carbon with the elements of water, 
and an excess of hydrogen. Such are the volatile 
and fixed oils, wax, and the resins. Many of them 
have acid characters. 

The juices of all vegetables contain organic acids, 
generally combined with the inorganic bases, or me- 
tallic oxides; for these metallic oxides exist in 
every plant, and may be detected in its ashes after 
incineration. 

Nitrogen is an element of vegetable albumen and 
gluten; it is a constituent of the acid, and of what 
are termed the " indifferent substances " of plants, 
as well as of those peculiar vegetable compounds 
which possess all the properties of metallic oxides, 
and are known as " organic bases." 

Estimated by its proportional weight, nitrogen 
forms only a very small part of plants ; but it is 
never entirely absent from any part of them. Even 
when it does not absolutely enter into the composi- 
tion of a particular part or organ, it is always to be 
found in the fluids which pervade it. 

It follows from the facts th\is far detailed, that 
the development of a plant requires the presence, 
first, of substances containing carbon and nitrogen, 
and capable of yielding these elements to the grow- 
ing organism; secondly, of water and its elements; 
and lastly, of a soil to furnish the inorganic matters 
which are likewise essential to vegetable life. 



OF THE COMPOSITION OF THE ATMOSPHERE. 

In the normal state of growth, plants can only 
derive their nourishment from the atmosphere and 
the soil. Hence it is of importance to be acquainted 
with the composition of these, in order that we may 
be enabled to judge from which of their constituents 
the nourishment is afforded. 

The composition of the atmosphere has been exam- 



28 OF THE COMPOSITION OF THE ATMOSPHERE. 

iiied by many chemists with great care, and the results 
of their researches have shown, that its principal 
constituents are always present in the same propor- 
tion. These are the two gases, oxygen and nitro- 
gen, the general properties of which have been 
already described. One hundred parts, by weight, 
of atmospheric air contain 23-1 parts of oxygen, 
and 76-9 parts of nitrogen ; or 100 volumes of air 
contain nearly 21 volumes of oxygen gas. From 
the extensive range of affinity which this gas pos- 
sesses, it is obvious, that were it alone to constitute 
our atmosphere, and left unchecked to exert its 
powerful effects, all nature would be one scene of 
universal destruction. It is on this account that 
nitrogen is present in the air in so large proportion. 
It is peculiarly adapted for this purpose, as it does 
not possess any disposition to unite with oxygen, 
and exerts no action upon the processes proceeding 
on the earth. These two gases are intimately mixed, 
by virtue of a property which .all gases possess in 
common, of diffusing themselves equally through 
every part of another gas, with which they are 
placed in contact. 

Although oxygen and nitrogen form the principal 
constituents of the atmosphere, yet they are not the 
only substances found in it. Watery vapor and 
carbonic acid gas materially modify its properties. 
The former of these falls upon the earth as rain, and 
brings with it any soluble matter which it meets in 
its passage through the air. 

Carbonic acid gas is discharged in immense quan- 
tities from the active volcanoes of America, and 
from many of the mineral springs which abound in 
various parts of Europe; it is also generated during 
the combustion and decay of organic matter. It is 
not, therefore, surprising that it should have been 
detected in every part of the atmosphere in which 
its presence has been looked for. Saussui*e found it 
even in the air on the summit of Mont Blanc, which 
is covered with perpetual snow, and where it could 



OF SOILS. 29 

not have been produced by the immediate agency of 
vegetable matter. Carbonic acid gas performs a 
most important part in the process of vegetable 
nutrition, the consideration of which belongs to 
another part of the work. 

Carbonic acid, water, and ammonia (a compound 
of hydrogen and nitrogen) are the final products of 
the decay of animal and vegetable matter. In an 
isolated condition, they usually exist in the gaseous 
form. Hence, on their formation, they must escape 
into the atmosphere. But ammonia has not hitherto 
been enumerated amongst the constituents of the 
air, although, according to our view, it can never be 
absent. The reason of this is, that it exists in 
extremely minute quantity in the amount of air usu- 
ally subjected to experiment in chemical analysis ; 
it has consequently escaped detection. But rain 
which falls through a large extent of air, carries 
down in solution all that remains in suspension in it. 
Now ammonia always exists in rain-water, and from 
this fact we must conclude that it is invariably pres- 
ent in the atmosphere. Nor can we be surprised at 
its presence when we consider that many volcanoes 
now in activity emit large quantities of it.* This 
subject will, however, be discussed more fully in 
another part of the work. 

Such are the principal constituents of the atmo- 
sphere from which plants derive their nourishment; 
for although other matters are supposed to exist in 
it in minute quantity, yet they do not exercise any 
influence on vegetation, nor has even their presence 
been satisfactorily demonstrated. 



OF SOILS. 



A soil may be considered a magazine of inorganic 
matters, which are prepared by the plant to suit the 

* The annual evolution of carbonic acid from springs and fissures in the 
ancient volcanic district of the EilLi, on the Rhine, has been estimated by 
Bischof, at not less than 100,000 tons, containing 27,000 tons of carbon. 

3* 



30 OF THE ASSIMILATION OF CARBON. 

purposes for which they are destined in its nutrition. 
The composition and uses of such substances cannot, 
however, be studied with advantage, until we have 
considered the manner in which the organic matter 
is obtained by plants. 

Some virgin soils, such as those of America, con- 
tain vegetable matter in large proportion ; and as 
these have been found eminently adapted for the 
cultivation of most plants, the organic matter con- 
tained in them has naturally been recognised as the 
cause of their fertility. T.o this matter, the term 
" vegetable mould " or humus has been applied. 
Indeed, this peculiar substance appears to play such 
an important part in the phenomena of vegetation, 
that vegetable physiologists have been induced to 
ascribe the fertility of every soil to its presence. It 
is believed by many to be the principal nutriment of 
plants, and is supposed to be extracted by them 
from the soil in which they grow. It is itself the 
product of the decay of vegetable matter, and must 
therefore contain many of the constituents which 
are found in plants during life. Its action will 
therefore be examined in considering whence these 
constituents are derived. 



CHAPTER II. 

OF THE ASSIMILATION OF CARBON. 



COMPOSITION OF HUMUS. 

The humus, to which allusion has been made, is 
described by chemists as a brow^n substance easily 
soluble in alkalies, but only slightly so in water, and 
produced during the decomposition of vegetable 
matters by the action of acids or alkalies. It has, 
however, received various names according. to the 
different external characters and chemical properties 
which it presents. Thus, ulmin, humic acid, coal of 



COMPOSITION OF HUMUS. 31 

humus, and humin, are names applied to modifica- 
tions of humus. They are obtained by treating peat, 
woody fibre, soot, or brown coal with alkalies ; by 
decomposing sugar, starch, or sugar of milk by 
means of acids ; or by exposing alkaline solutions of 
tannic and gallic acids to the action of the air. 

The modifications of /minus which are soluble in 
alkalies, are called humic acid; while those which 
are insoluble have received the designations oi humin 
and coal of humus* 

The names given to these substances might cause 
it to be supposed that their composition is identical. 
But a more erroneous notion could not be enter- 
tained ; since even sugar, acetic acid, and resin do 
not differ more widely in the proportions of their 
constituent elements, than do the various modifica- 
tions of humus. 

Humic acid formed by the action of hydrate f of 

* The soluble matters were formerly called by the eminent Swedish 
chemist Berzelius, extract of humus, and the insoluble geine (from the 
Greek yij, the earth), also apoiheme and carlonaceous hvmvs. This 
substance is now known to be composed of various ingredients, and of 
these the two acids, which have received the names of Crenic and 
Jipocrcnic, are particularly interesting. 

See Professor Hitchcock's Report, and American Joxirnal of Science, 
Vol. XXXVI., Art. XII. 

Dr. S. L. Dana considers geine as forming the basis of all the nour- 
ishing part of all vegetable manures, and, in the three states of " vegeta- 
ble extract, geine, and carbonaceous mould," to be the principle which 
gives fertilit}' to soils long after the action of common manures has 
ceased. See Report on the reexaminntion of the Economical Geology 
of Massachusetts. In the Third Report on the Agriculture of the Slate 
of Massachusetts, 1840, Dr. Dana remarks, that geine "is the decom- 
posed organic matter of the soil. It is the product of putrefaction; 
continually subjected to air and moisture, it is finally wholly dissipated 
in air, leaving only the inorganic bases of the plant, with which it was 
once combined. Now, whether we consider this as a simple substance, 
or composed of several others, called crenic, apocrenic, puteanic, ulmic 
acids, glairin, apotheme, extract, humus, or mould, agriculture ever 
has and probably ever will consider it one and the same thing, requir- 
ing always similar treatment to produce it; similar treatment to render 
it soluble when produced; similar treatment to render it an effectual 
manure. It is the end of all compost heaps to produce soluble geine, 
no matter how compound our chemistry may teach this substance to 
be." Page 191. 

t Hydrates are compounds of oxides, salts, &c., with definite quan- 
tities of water, — a substance from which all the water has been re- 
moved is anhydrous. Even after exposure to a red heat, caustic potash 
retains water. 



32 OF THE ASSIMILATION OF CARBON. 

potash upon sawdust contains, according to the 
accurate analysis of Peligot, 72 per cent, of carbon, 
while the humic acid obtained from turf and brown 
coal contains, according to Sprengel, only 58 per 
cent. ; that produced by the action of dilute sul- 
phuric acid upon sugar, 57 per cent, according to 
Malaguti ; and that, lastly, which is obtained from 
sugar or from starch, by means of muriatic acid, 
according to the analysis of Stein, 64 per cent. All 
these analyses have been repeated with care and 
accuracy, and the proportion of carbon in the re- 
spective cases has been found to agree with the 
estimates of the different chemists above mentioned; 
so that there is no reason to ascribe the difference 
in this respect between the varieties of humus to 
the mere difference in the methods of analysis or 
degrees of expertness of the operators. Malaguti 
states, moreover, that humic acid contains an equal 
number of equivalents of oxygen and hydrogen, that 
is to say, that these elements exist in it in the pro- 
portions for forming water ; while, according to 
Sprengel, the oxygen is in excess, and Peligot even 
estimates the quantity of oxygen at 14 equivalents, 
and the hydrogen at only 6 equivalents, making the 
deficiency of hydrogen as great as 8 equivalents. 
And although Mulder* has very recently explained 
many of these conflicting results, by showing that 
there are several kinds of humus and humic acids 
essentially distinct in their characters, and fixed in 
their composition, yet he has afforded no proof that 
the definite compounds obtained by him really exist, 
as such, in the soil. On the contrary, they appear 
to have been formed by the action of the potash and 
ammonia, which he employed in their preparation. 

It is quite evident, therefore, that chemists have 
been in the habit of designating all products of the 
decomposition of organic bodies which had a brown 
or brownish-black color by the names of humic 

* Bulletin des Scienc. Phys. et Natur. de Neerl.1840, p. 1-102. 



PROPERTIES OF HUMUS. 33 

acid or humin, according as they were soluble or 
insoluble in alkalies ; although in their composition 
and mode of origin, the substances thus confounded 
might be in no way allied. 

Not the slightest ground exists for the belief that 
one or other of these artificial products of the de- 
composition of vegetable matters exists in nature in 
the form and endowed with the properties of the 
vegetable constituents of mould; there is not the 
shadow of a proof that one of them exerts any influ- 
ence on the growth of plants either in the way of 
nourishment or otherwise. 

Vegetable physiologists have, without any appar- 
ent reason, imputed the known properties of the 
humus and huniic acids of chemists to that constitu- 
ent of mould which has received the same name, and 
in this way have been led to their theoretical notions 
respecting the functions of the latter substance in 
vegetation. 

The opinion, that the substance called humus is 
extracted from the soil by the roots of plants, and 
that the carbon entering into its composition serves 
in some form or other to nourish their tissues, is 
considered by many as so firmly established, that any 
new argument in its favor has been deemed unneces- 
sary; the obvious difference in the growth of plants, 
according to the known abundance or scarcity of 
himms in the soil, seemed to afford incontestable 
proof of its correctness.* 

Yet, this position, when submitted to a strict ex- 
amination, is found to be untenable, and it becomes 
evident, from most conclusive proofs, that humus, in 
the form in which it exists in the soil, does not yield 
the smallest nourishment to plants. 

The adherence to the above incorrect opinion has 

* This remark applies more to German than to English botanists and 
physiologists. In England, the idea that humus, as such, affords nour- 
ishment to plants is by no means general ; but on the Continent, the 
views of Berzelius on this subject have been almost universally adopt- 
ed.— Ed. 



34 OF THE ASSIMILATION OF CARBON. 

hitherto rendered it impossible for the true theory 
of the nutritive process in vegetables to become 
known, and has thus deprived us of our best guide 
to a rational practice in agriculture. Any great im- 
provement in that most important of all arts is in- 
conceivable, without a deeper and more perfect ac- 
quaintance with the substances which nourish plants, 
and with the sources whence they are derived ; and 
no other cause can be discovered to account for the 
fluctuating and uncertain state of our knowledge on 
this subject up to the present time, than that modern 
physiology has not kept pace with the rapid progress 
of chemistry. 

In the following inquiry, we shall suppose the hu- 
mus of vegetable physiologists to be really endowed 
with the properties recognised by chemists in the 
brownish black deposits, which they obtain by pre- 
cipitating an alkaline decoction of mould or peat by 
means of acids, and which they name fuimic acid.* 

Humic acid, when first precipitated, is a flocculent 
substance, is soluble in 2500 times its weight of wa- 
ter, and combines with alkalies, lime and magnesia, 
forming compounds of the same degree of solubility. 
(Sprengel.) 

Vegetable physiologists agree in the supposition 
that by the aid of water hiimvs is rendered capable 

* The extract obtained by Berzelins from black, brownish soils has 
been designated as humic extract, in some cases with a substance called 
glair in. The glairin is described by Thomson as a peculiar substance 
which has been observed in certain sulphureous mineral waters, and 
was first noticed by Vauquelin {Jinn, de Chim. XXXIX. 171-!), who de- 
scribed several of its properties and considered it analogous to gelatin. 
An account of it was drawn up by M. Anglada, of Montpellier, and 
communicated to the Royal Academy of Medicine of Paris, in 1827. It 
gelatinizes with water when sufficiently concentrated. Sometimes it is 
white, and at others of a red color ; when dried it shrinks to j'^th of its 
bulk when moist. It saturates ammonia, and decomposes several me- 
tallic salts. It is destitute of smell and taste. It does not glue sub- 
stances together like gelatin and albumen. It yields ammonia by de- 
composition, and is capable of putrefaction like animal bodies. The 
general opinion is, that it is of vegetable origin, and allied to the genus 
tremella, though its existence in mineral waters has not been account- 
ed for. Thomson's Organic Chemistry., 694. I found it very abun- 
dant about the hot sulphureous waters of the island of St. Michael, 
Azores. — W. 



ABSORPTION OF HUMUS. 35 

of being absorbed by the roots of plants. But ac- 
cording to the observation of chemists, humic acid is 
soluble only when newly precipitated, and becomes 
completely insoluble when dried in the air, or when 
exposed in the moist state to the freezing tempera- 
ture. (Sprengel.) 

Both the cold of winter and the heat of summer 
therefore are destructive of the solubility of humic 
acid, and at the same time of its capability of being 
assimilated by plants. So that, if it is absorbed by 
plants, it must be in some altered form. 

The correctness of these observations is easily 
demonstrated by treating a portion of good mould 
with cold water. The fluid remains colorless, and is 
found to have dissolved less than 100,000 part of its 
weight of organic matters, and to contain merely the 
salts which are present in rain-water. 

Decayed oak-wood, likewise, of which humic acid 
is the principal constituent, was found by Berzelius 
to yield to cold water only slight traces of soluble 
materials ; and I have myself verified this observa- 
tion on the decayed wood of beech and fir. 

These facts, which show that humic acid, in its 
unaltered condition, cannot serve for the nourishment 
of plants, have not escaped the notice of physiolo- 
gists ; and hence they have assumed that the lime or 
the different alkalies, found in the ashes of vegeta- 
bles, render soluble the humic acid and fit it for the 
process of assimilation. 

Alkalies and alkaline earths do exist in the differ- 
ent kinds of soil in sufficient quantity to form such 
soluble compounds with the humic acid. 

Now, let us suppose that humic acid is absorbed 
by plants in the form of that salt which contains the 
largest proportion of humic acid, namely, in the form 
of humate of lime, and then, from the known quantity 
of the alkaline bases contained in the ashes of plants, 
let us calculate the amount of humic acid which 
might be assimilated in this manner. Let us admit, 
likewise, that potash, soda, and the oxides of iron 



36 OF THE ASSIMILATION OF CAKBOM. 

and manganese have the same capacity of saturation 
as lime with respect to humic acid, and then we may 
take as the basis of our calculation the analysis of 
M. Berthier, who found that 1000 lbs. of dry fir-wood 
yielded 4 lbs. of ashes, and that in every 100 lbs. of 
these ashes, after the chloride of potassium and sul- 
phate of potash were extracted, 53 lbs. consisted of 
the basic metallic oxides, potash, soda, lime, magne- 
sia, iron, and manganese. 

One Hessian acre* of woodland yields annually, 
according to Dr. Heyer, on an average, 2920 lbs. of 
dry fir-wood, which contain 6.17 lbs. of metallic 
oxides. 

Now, according to the estimates of Malaguti and 
Sprengel, 1 lb. of lime combines chemically with 12 
lbs. of humic acid; 6.17 lbs. of the metallic oxides 
would accordingly introduce into the trees 74.04 of 
humic acid, which, admitting humic acid to contain 
58 per cent, of carbon, would correspond to 100 lbs. 
of dry wood. But we have seen that 2920 lbs. of 
fir-wood are really produced. 

Again, if the quantity of humic acid which might 
be introduced into wheat in the form of humates is 
calculated from the known proportion of metallic 
oxides existing in wheat straw, (the sulphates and 
chlorides also contained in the ashes of the straw 
not being included,) it will be found that the w^heat 
growing on 1 Hessian acre would receive in that 
way 63 lbs. of humic acid, corresponding to 93,6 lbs. 
of woody fibre. But the extent of land just men- 
tioned produces, independently of the roots and 
grain, 1961 lbs. of straw, the composition of which 
is the same as that of woody fibre. 

It has been taken for granted in these calculations 
that the basic metallic oxides which have served to 
introduce humic acid into the plants do not return 
to the soil, since it is certain that they remain fixed 

* One Hessian acre is equal to 40,000 square feet, Hessian, or 26,910 
square feet, English measure P. 



ABSORPTION OF HUMUS. 37 

in the parts newly formed during the process of 
growth. 

Let us now calculate the quantity of humic acid 
which plants can receive under the most favorable 
circumstances, viz., through the agency of rain- 
water. 

The quantity of rain which falls at Erfurt, one of 
the most fertile districts of Germany, during the 
months of April, May, June, and July, is stated by 
Schubler to be 19.3 lbs. over every square foot of 
surface; 1 Hessian acre, or 26,910 square feet, con- 
sequently receive 519,363 lbs. of rain-water. 

If, now, we suppose that the whole quantity of 
this rain is taken up by the roots of a summer plant, 
which ripens four months after it is planted, so that 
not a pound of this water evaporates except from 
the leaves of the plant ; and if we further assume 
that the water thus absorbed is saturated with 
humate of lime (the most soluble of the huraates, 
and that which contains the largest proportion of 
humic acid) ; then the plants thus nourished would 
not receive more than 330 lbs. of humic acid, since 
one part of humate of lime requires 2500 parts of 
water for solution. 

But the extent of land which we have mentioned 
produces 2843 lbs. of corn (in grain and straw, the 
roots not included), or 22,000 lbs. of beet-root 
(without the leaves and small radical fibres). It is 
quite evident that the 330 lbs. of humic acid, sup- 
posed to be absorbed, cannot account for the quan- 
tity of carbon contained in the roots and leaves 
alone, even if the supposition were correct, that the 
whole of the rain-water was absorbed by the plants. 
But since it is known that only a small portion of 
the rain-water which falls upon the surface of the 
earth evaporates through plants, the quantity of 
carbon which can be conveyed into them in any 
conceivable manner by means of humic acid must be 
extremely trifling, in comparison with that actually 
produced in vegetation. 
4 



38 OF THE ASSIMILATION OF CARBON. 

Other considei'ations of a higher nature confute 
the common view respecting the nutritive office of 
humic acid, in a manner so clear and conclusive that 
it is difficult to conceive how it could have been so 
generally adopted. 

Fertile land produces carbon in the form of wood, 
hay, grain, and other kinds of growth, the masses 
of which differ in a remarkable degree. 

2920 lbs. of firs, pines, beeches, &c. grow as wood 
upon one Hessian acre of forest-land with an average 
soil. The same superficies yields 2755 lbs. of hay. 

A similar surface of corn-land gives from 19,000 
to 22,004 lbs. of beet-root, or 881 lbs. of rye, and 
1961 lbs. of straw, 160 sheaves of 15.4 lbs. each, — 
in all, 2843 lbs. 

One hundred parts of dry fir-wood contain 38 
parts of carbon ; therefore, 2920 lbs. contain 1109 
lbs. of carbon. 

One hundred parts of hay,* dried in air, contain 
44.31 parts carbon. Accordingly, 2755 lbs. of hay 
contain 1110 lbs. of carbon. 

Beet-roots contain from 89 to 89.5 parts water, 
and from 10.5 to 11 parts solid matter, which con- 
sists of from 8 to 9 per cent, sugar, and from 2 to 
2| per cent, cellular tissue. Sugar contains 42.4 
per cent.; cellular tissue, 47 per cent, of carbon. 

22,004 lbs. of beet-root, therefore, if they contain 
9 per cent, of sugar, and 2 per cent, of cellular tis- 
sue, would yield 1031 lbs. of carbon, of which 833 
lbs. would be due to the sugar, and 198 lbs. to the 
cellular tissue ; the carbon of the leaves and small 
roots not being included in the calculation. 

One hundred parts of straw ,f dried in air, contain 

* 1(30 parts of hay, dried at 100° C. (212° F.) and burned with oxide 
of copper in a stream of oxygen gas, yielded 5193 water, 165-8 car- 
bonic acid, and G-82 of ashes. This gives 45 87 carbon, 5 76 hydrogen, 
31"55 oxygen, and 6 82 ashes. Hay, dried in the air, loses 11-2 p. c. 
water at 100° C. (212 F. ) — {Dr. UlU.) 

t Straw analyzed in the same manner, and dried at 100° C, gave 
46 37 p. c. of carbon, 5 08 p. c. of hydrogen, 43 93 p. c. of oxygen, and 
4-02 p. c of ashes. Straw dried in the air at 100° C. lost IS p. c. of 
water. — (Dr. Will.) 



FERTILITY OF DIFFERENT SOILS. 39 

38 per cent, of carbon; therefore 1961 lbs. of straw 
contain 745 lbs. of carbon. One hundred parts of 
corn contain 43 parts of carbon; 882 lbs. must 
therefore contain 379 lbs., — in all, 1124 lbs. of car- 
bon. 

26,910 square feet of wood and meadow land pro- 
duce, consequently, 1109 lbs. of carbon; while the 
same extent of arable land yields in beet-root, 
without leaves, 1032 lbs., or in corn, 1124 lbs. 

It must be concluded from these incontestable 
facts, that equal surfaces of cultivated land of an 
average fertility produce equal quantities of carbon; 
yet, how unlike have been the different conditions 
of the growth of the plants from which this has 
been deduced ! 

Let us now inquire whence the grass in a meadow, 
or the wood in a forest, receives its carbon, since 
there no manure — no carbon — has been given to it 
as nourishment 1 and how it happens, that the soil, 
thus exhausted, instead of becoming poorer, becomes 
every year richer in this element 1 

A certain quantity of carbon is taken every year 
from the forest or meadow, in the form of wood or 
hay, and, in spite of this, the quantity of carbon in 
the soil augments ; it becomes richer in humus. 

It is said that in fields and orchards all the carbon 
which may have been taken away as herbs, as straw, 
as seeds, or as fruit, is replaced by means of manure; 
and yet this soil produces no more carbon than that 
of the forest or meadow, where it is never replaced. 
It cannot be conceived that the laws for the nutri- 
tion of plants are changed by culture, — that the 
sources of carbon for fruit or grain, and for grass or 
trees, are different. 

It is not denied that manure exercises an influence 
upon the development of plants ; but it may be 
affirmed with positive certainty, that it neither serves 
for the production of the carbon, nor has any influ- 
ence upon it, because we find that the quantity of 
carbon produced by manured lands is not greater 



40 OF THE ASSIMILATION OF CARBON. 

than that yielded by lands which are not manured. 
The discussion as to the manner in which manure 
acts has nothing to do with the present question, 
which is, the orio-in of the carbon. The carbon must 
be derived from other sources ; and as the soil does 
not yield it, it can only be extracted from the atmo- 
sphere. 

In attempting to explain the origin of carbon in 
plants, it has never been considered that the ques- 
tion is intimately connected with that of the origin 
of humus. It is universally admitted that humus 
arises from the decay of plants. No primitive 
humus, therefore, can have existed, — for plants must 
have preceded the humus. 

Now, whence did the first vegetables derive their 
carbon ? and in what form is the carbon contained 
in the atmosphere ? 

These two questions involve the consideration of 
two most remarkable natural phenomena, which by 
their reciprocal and uninterrupted influence maintain 
the life of the individual animals and vegetables, 
and the continued existence of both kingdoms of 
organic nature. 

One of these questions is connected with the inva- 
riable condition of the air with respect to oxygen. 
One hundred volumes of air have been found, at 
every period and in every climate, to contain 21 
volumes of oxygen, with such small deviations that 
they must be ascribed to errors of observation. 

Although the absolute quantity of oxygen con- 
tained in the atmosphere appears very great when 
represented by numbers, yet it is not inexhaustible. 
One man consumes by respiration 25 cubic feet of 
oxygen in 24 hours ; 10 cwt. of charcoal consume 
32,066 cubic feet of oxygen during its combustion ; 
and a small town like Giessen (with about 7000 
inhabitants) extracts yearly from the air, by the 
wood employed as fuel, more than 551 millions of 
cubic feet of this gas. 

When we consider facts such as these, our former 



QUANTITY OF OXYGEN IN THE ATMOSPHERE. 41 

statement, that the quantity of oxygen in the atmo- 
sphere does not diminish in the course of ages,* — 
that the air at the present day, for example, does 
not contain less oxygen than that found in jars 
buried for 1800 years in Pompeii, — appears quite 
incomprehensible, unless some source exists whence 
the oxygen abstracted is replaced. How does it 
happen, then, that the proportion of oxygen in the 
atmosphere is thus invariable ? 

The answer to this question depends upon another j 
namely, what becomes of the carbonic acid, which is 
produced during the respiration of animals, and by 
the process of combustion ? A cubic foot of oxygen 
gas, by uniting with carbon so as to form carbonic 
acid, does not change its volume. The billions of 
cubic feet of oxygen extracted from the atmosphere, 
produce the same number of billions of cubic feet 

* If the atmosphere possessed, in its whole extent, the same density 
as it does on the surface of the sea, it would have a height of 24,555 
Parisian feet; but it contains the vapor of water, so that we may as- 
sume its height to be one geographical mile = 22,843 Parisian feet. Now 
the radius of the earth is equal to 8G0 geographical miles ; hence the 
Volume of the atmosphere = 9,:507,500 cubic miles. 

= cube of 210-4 miles. 
Volume of oxygen . . = 1,954,578 cubic miles. 

= cube of 125 miles. 
Volume of carbonic acid = 3,862-7 cubic miles. 
= cube of 15-7 miles. 
The maximum of the carbonic acid contained in the atmosphere has 
not here been adopted, but the mean, which is equal to 0-000415. (L.) The 
weight of carbon which presses upon each square inch of the earth's 
surface being 17'39 grains, on an acre of land will be 7 tons. — (Johnston.) 
A man daily consumes 45,000 cubic inches (Parisian). A man 
yearly consumes 9505-2 cubic feet. 100 million men yearly consume 
9,505,200,000,000 cubic feet. 

Hence a thousand million men yearly consume 0-79745 cubic miles 
of oxj^gen. But the air is rendered incapable of supporting the pro- 
cess of respiration, when the quantity of its oxygen is decreased 12 
percent.; so that a thousand million men would make the air unfit 
for respiration in a million years. The consumption of oxygen by 
animals, and by the process of combustion, is not introduced into the 
calculation. 

When the air returns from the lungs, the carbonic acid gas amounts, 
on an average, to jjth of the whole ; or its quantity is increased one 
hundred times. — (Johnston.) A full grown man gives off from his 
lungs, in the course of a year, upwards of lllO lbs. of carbon. It is 
estimated by Johnston, that at least one third of the carbon of the 
food of men is daily returned to the air. 
4* 



42 OF THE ASSIMILATION OF CARBON. 

of carbonic acid, which immediately supply its 
place. 

The most exact and most recent experiments of 
De Saussure, made in every season for a space of 
three years, have shown, that the air contains on an 
averajie 0-000415 of its own volume of carbonic acid 
gas ; so that, allowing for the inaccuracies of the 
experiments, which must diminish the quantity ob- 
tained, the proportion of carbonic acid in the atmo- 
sphere may be regarded as nearly equal to jgosth part 
of its weight. The quantity varies according to the 
seasons ; but the yearly average remains continually 
the same. 

We have no reason to believe that this proportion 
was less in past ages; and nevertheless, the im- 
mense masses of carbonic acid which annually flow 
into the atmosphere from so many sources, ought per- 
ceptibly to increase its quantity from year to year. 
But we find that all earlier observers describe its 
volume as from one-half to ten times greater than 
that which it has at the present time ; so that we can 
hence at most conclude that it has diminished. 

It is quite evident that the quantities of carbonic 
acid and oxygen in the atmosphere, which remain 
unchanged by lapse of time, must stand in some fixed 
relation to one another; a cause must exist which 
prevents the increase of carbonic acid by removing 
that which is constantly forming ; and there must be 
some means of replacing the oxygen, which is re- 
moved from the air by the processes of combustion 
and putrefaction, as well as by the respiration of 
animals. 

Both these causes are united in the process of 
vegetable life. 

The facts which we have stated in the preceding 
pages prove, that the carbon of plants must be de- 
rived exclusively from the atmosphere. Now, carbon 
exists in the atmosphere only in the form of carbonic 
acid, and therefore in a state of combination with 
oxygen. 



LIBERATION OF OXYGEN. 43 

It has been already mentioned likewise, that car- 
bon and the elements of water form the principal 
constituents of vegetables; the quantity of the sub- 
stances which do not possess this composition being 
in a very small proportion. Now, the relative quan- 
tity of oxygen in the whole mass is less than in car- 
bonic acid; for the latter contains two equivalents 
of oxygen, whilst one only is required to unite with 
hydrogen in the proportion to form water. The veg- 
etable products which contain oxygen in larger pro- 
portion than this, are, comparatively, few in number; 
indeed in many the hydrogen is in great excess. It 
is obvious, that when the hydrogen of water is as- 
similated by a plant, the oxygen in combination with 
it must be liberated, and will afford a quantity of 
this element sufficient for the wants of the plants. 
If this be the case, the oxygen contained in the car- 
bonic acid is quite unnecessary in the process of 
vegetable nutrition, and it will consequently escape 
into the atmosphere in a gaseous form. It is there- 
fore certain, that plants must possess the power of 
decomposing carbonic acid, since they appropriate 
its carbon for their own use. The formation of their 
principal component substances must necessarily be 
attended with the separation of the carbon of the 
carbonic acid fram the oxygen, which must be re- 
turned to the atmosphere, whilst the carbon enters 
into combination with water or its elements. The 
atmosphere must thus receive a volume of oxygen 
for every volume of carbonic acid which has been 
decomposed. 

This remarkable property of plants has been de- 
monstrated in the most certain manner, and it is in 
the power of every person to convince" himself of its 
existence. The leaves and other green parts of a 
plant absorb carbonic acid, and emit an equal volume 
of oxygen. They possess this property quite inde- 
pendently of the plant ; for if, after being separated 
from the stem, they are placed in water containing 
carbonic acid, and exposed in that condition to the 



44 OF THE ASSIMILATION OF CARBON. 

sun's light, the carbonic acid is, after a time, found 
to have disappeared entirely from the water. If the 
experiment is conducted under a glass receiver filled 
with water, the -oxygen emitted from the plant may 
be collected and examined. When no more oxygen 
gas is evolved, it is a sign that all the dissolved car- 
bonic acid is decomposed ; but the operation recom- 
mences if a new portion of it is added. 

Plants do not emit gas when placed in water which 
either is free from carbonic acid, or contains an al- 
kali that protects it from assimilation. 

These observations were first made by Priestley 
and Sennebier. The excellent experiments of De 
Saussure have further shown, that plants increase in 
weight during the decomposition of carbonic acid 
and separation of oxygen. This increase in weight 
is greater than can be accounted for by the quantity 
of carbon assimilated ; a fact which confirms the 
view, that the elements of water are assimilated at 
the same time. 

The life of plants is closely connected with that 
of animals, in a most simple manner, and for a wise 
and sublime purpose. 

The presence of a rich and luxuriant vegetation 
may be conceived without the concurrence of animal 
life, but the existence of animals is undoubtedly de- 
pendent upon the life and development of plants. 

Plants not only afford the means of nutrition for 
the growth and continuance of animal organization, 
but they likewise furnish that which is essential for 
the support of the important vital process of respira- 
tion ; for besides separating all noxious matters from 
the atmosphere, they are an inexhaustible source of 
pure oxygen, which supplies the loss which the air 
is constantly sustaining. Animals on the other hand 
expire carbon, which plants inspire ; and thus the 
composition of the medium in which both exist, name- 
ly, the atmosphere, is maintained constantly un- 
changed. 

It may be asked, — Is the quantity of carbonic acid 



ITS SOURCE THE ATMOSPHERE. 45 

in the atmosphere, which scarcely amounts to i^th. 
per cent., sufficient for the wants of the whole vege- 
tation on the surface of the earth, — is it possible 
that the carbon of plants has its origin from the air 
alone ? This question is very easily answered. It 
is known, that a column of air of 2441 lbs. weight 
rests upon every square Hessian foot (=0-567 square 
foot English) of the surface of the earth; the diame- 
ter of the earth and its superficies are likewise known, 
so that the weight of the atmosphere can be calcu- 
lated with the greatest exactness. The thousandth 
part of this is carbonic acid, which contains upwards 
of 27 per cent, carbon. By this calculation it 
can be shown, that the atmosphere contains 3306 
billion lbs. of carbon ; a quantity which amounts to 
more than the weight of all the plants, and of all the 
strata of mineral and brown coal, which exist upon 
the earth. This carbon is, therefore, more than ade- 
quate to all the purposes for which it is required. 
The quantity of carbon contained in sea-water is 
proportionally still greater. 

If, for the sake of argument, we suppose the su 
perficies of the leaves and other green parts of plants 
by which the absorption of carbonic acid is effected, 
to be double that of the soil upon which they grow, 
a supposition which is much under the truth in the 
case of woods, meadows, and corn-fields ; and if we 
further suppose that carbonic acid equal to 0'00067 
of the volume of the air, or i^o^^^ of its weight, 
is abstracted from it during every second of time, 
for eight hours daily, by a field of 53,820 square feet 
{ = 2 Hessian acres) ; then those leaves would re- 
ceive 1102 lbs. of carbon in 200 days.* 

* The qu<antity of carbonic acid which can be extracted from the air 
in a given time, is shown by the following calculation. During the 
white- wasiiing of a small ciiamber, tlie superficies of the walls and roof 
of which we will suppose to be 105 square metres, and which receives 
six coats of lime in four days, carbonic acid is abstracted from the air, 
and the lime is consequently converted, on the surface, into a carbon- 
ate. It has been accurately determined that one square decimetre re- 
ceives in this way, a coating of carbonate of lime which weighs 0-732 
grammes. Upon the 105 square metres already mentioned there must 



46 OF THE ASSIMILATION OF CARBON. 

But it is inconceivable, that the functions of the 
organs of a plant can cease for any one moment 
during its life. The roots and other parts of it, 
which possess the same power, absorb constantly 
water and carbonic acid. This power is independ- 
ent of solar light. During the day, w^hen plants are 
in the shade, and during the night, carbonic acid is 
accumulated in all parts of their structure; and the 
assimilation of the carbon and the exhalation of 
oxygen commence from the instant that the rays of 
the sun strike them. As soon as a young plant 
breaks through the surface of the ground, it begins 
to acquire color from the top downwards ; and the 
true formation of woody tissue commences at the 
same time.* 

The proper, constant, and inexhaustible sources 
of oxygen gas are the tropics and warm climates, 
where a sky, seldom clouded, permits the glowing 
rays of the sun to shine upon an immeasurably 
luxuriant vegetation. The temperate and cold zones, 
where artificial warmth must replace deficient heat 
of the sun, produce, on the contrary, carbonic acid 
in superabundance, which is expended in the nutri- 
tion of the tropical plants. The same stream of 
air, which moves by the revolution of the earth from 
the equator to the poles, brings to us, in its passage 
from the equator, the oxygen generated there, and 
carries away the carbonic acid formed during our 
winter. 



accordingly be formed 76S6 grammes of carbonate of lime, which con- 
tain 43'25-6 grammes of carbonic acid. The weight of one cubic deci- 
metre of carbonic acid being calculated at two grammes, (more accu- 
rately 1-07978,) the above-mentioned surface must absorb in four days 
2-1G3 cubic metres of carbonic acid. 2500 square metres (one Hessian 
acre) would absorb, under a similar treatment, olj cubic metres = 1818 
cubic feet of carbonic acid in four days. In 200 days it would absorb 
2575 cubic metres =: 904,401 cubic feet, which contain 1 1 ,353 lbs. of 
carbonic acid, of which 3304 lbs. are carbon, a quantity three times as 
great as that which is assimilated by the leaves and roots growing upon 
the same space. — L. 

* Plants that grow in the dark, are well known to be colorless. This 
is seen in the blanching of celery (etiolation), the earth is heaped 
around the stalks to exclude the light. 



ITS SOURCE THE ATMOSPHERE.. 47 

The experiments of De Saussure have proved, 
that the upper strata of the air contain more car- 
bonic acid than the lower, which are in contact with 
plants; and that the quantity is greater by night 
than by day, when it undergoes decomposition. 

Plants thus improve the air, by the removal of 
carbonic acid, and by the renewal of oxygen, which 
is immediately applied to the use of man and animals. 
The horizontal currents of the atmosphere bring 
with them as much as they carry away, and the in- 
terchange of air between the upper and lower strata, 
which their difference of temperature causes, is 
extremely trifling when compared with the horizon- 
tal movements of the winds. Thus vegetable culture 
heightens the healthy state of a country, and a 
previously healthy country would be rendered quite 
uninhabitable by the cessation of all cultivation. 

The various layers of wood and mineral coal, as 
well as peat, form the remains of a primeval vegeta- 
tion. The carbon which they contain must have 
been originally in the atmosphere as carbonic acid, 
in which form it was assimilated by the plants which 
constitute these formations. It follows from this, 
that the atmosphere must be richer in oxygen at the 
present time than in former periods of the earth's 
history. The increase must be exactly proportional 
to the quantity of carbon and hydrogen contained 
in these carboniferous deposits. Thus, during the 
formation of 353 cubic feet of Newcastle splint-coal, 
the atmosphere must have received 643 cubic feet 
of oxygen produced from the carbonic acid assim- 
ilated, and also 158 cubic feet of the same gas 
resulting from the decomposition of water. In 
former ages, therefore, the atmosphere must have 
contained less oxygen, but a much larger proportion 
of carbonic acid, than it does at the present time, 
a circumstance which accounts for the richness and 
luxuriance of the earlier vegetation. 

But a certain period must have arrived in which 
the quantity of carbonic acid contained in the air 



48 OF THE ASSIMILATION OF CARBON. 

experienced neither increase nor diminution in any- 
appreciable quantity. For if it received an addi- 
tional quantity to its usual proportion, an increased 
vegetation would be the natural consequence, and 
the excess would thus be speedily removed. And, 
on the other hand, if the gas was less than the 
normal quantity, the progress of vegetation would 
be retarded, and the proportion would soon attain 
its proper standard. 

The most important function in the life of plants, 
or, in other words, in their assimilation of carbon, 
is the separation, we might almost say, the genera- 
tion of oxygen. No matter can be considered as 
nutritious, or as necessary to the growth of plants, 
which possesses a composition either similar to or 
identical with theirs, and the assimilation of which, 
therefore, could take place without exercising this 
function. The reverse is the case in the nutrition 
of animals. Hence such substances as sugar, starch, 
and gum, which are themselves products of plants, 
cannot be adapted for assimilation. And this is 
rendered certain by the experiments of vegetable 
physiologists, who have shown that aqueous solutions 
of these bodies are imbibed by the roots of plants, 
and carried to all parts of their structure, but are 
not assimilated ; they cannot therefore be employed 
in their nutrition. We could scarcely conceive a 
form more convenient for assimilation than that of 
gum, starch, and sugar, for they all contain the 
elements of woody fibre, and nearly in the same pro- 
portions. 

In the second part of the work we shall adduce 
satisfactory proofs that decayed woody fibre (^hnmiis) 
contains carbon and the elements of water, without 
an excess of oxygen ; its composition differing from 
that of woody fibre in its being richer in carbon. 

Misled by this simplicity in its constitution, phy- 
siologists found no difficulty in discovering the mode 
of the formation of woody fibre ; for they say,* hu- 

* Meyen, Pflanzenphysiologie, II. S. 141. 



SEPARATION OF OXYGEN. 49 

mus has only to enter into combination with water, 
in order to effect the formation of woody fibre, and 
other substances similarly composed, such as sugar, 
starch, and gum. But they forget, that their own 
experiments have sufficiently demonstrated the inapt- 
itude of these substances for assimilation. 

All the erroneous opinions concerning the modus 
operandi of humus have their origin in the false 
notions entertained respecting the most important 
vital functions of plants; analogy, that fertile source 
of error, having, unfortunately, led to the very unapt 
comparison of the vital functions of plants with, 
those of animals. 

Substances, such as sugar, starch, &c., which con- 
tain carbon and the elements of water, are products 
of the life of plants which live only whilst they 
generate them. The same may be said of humus,, 
for it can be formed in plants like the former sub- 
stances. Smithson, Jameson, and Thomson, found 
that the black excretions of unhealthy elms, oaks, 
and horse-chesnuts, consisted of humic acid in com- 
bination with alkalies. Berzelius detected similar 
products in the bark of most trees. Now, can it be 
supposed that the diseased organs of a plant possess 
the power of generating the matter to which its 
sustenance and vigor are ascribed ? 

How does it happen, it may be asked, that the 
absorption of carbon from the atmosphere by plants 
is doubted by all botanists and vegetable physiolo- 
gists, and that by the greater number the purification 
of the air by means of them is wdiolly denied ? 

The action of plants on the air in the absence of 
light, that is during night, has been much miscon- 
ceived by botanists, and from this we may trace 
most of the errors which abound in the greater part 
of their writings. The experiments of Ingenhouss 
were in a great degree the cause of this uncertainty 
of opinion regarding the influence of plants in puri- 
fying the air. His observation, that green plants 
emit carbonic acid in the dark, led De Saussure and. 
5 



50 OF THE ASSIMILATION OF CARBON. 

Grischow to new investigations, by which they 
ascertained, that under such conditions plants do 
really absorb oxygen and emit carbonic acid; but 
that the whole volume of air undergoes diminution 
at the same time. From the latter fact it follows, 
that the quantity of oxygen gas absorbed is greater 
than the volume of carbonic acid separated ; for, if 
this were not the case, no diminution could occur. 
These facts cannot be doubted, but the views based 
on them have been so false, that nothing, except the 
total want of observation and the utmost ignorance 
of the chemical relations of plants to the atmo- 
sphere, can account for their adoption. 

It is known that nitrogen, hydrogen, and a num- 
ber of other gases, exercise a peculiar, and in gen- 
eral an injurious influence upon living plants. Is it, 
then, probable, that oxygen, one of the most ener- 
getic agents in nature, should remain without influ- 
ence on plants when one of their peculiar processes 
of assimilation has ceased 1 

It is true that the decomposition of carbonic acid 
is arrested by absence of light. But then, namely, 
at night, a true chemical process commences, in 
consequence of the action of the oxygen in the air, 
upon the organic substances composing the leaves, 
blossoms, and fruit. This process is not at all con- 
nected with the life of the vegetable organism, 
because it goes on in a dead plant exactly as in a 
living one. 

The substances composing the leaves of diff'erent 
plants being known, it is a matter of the greatest 
ease and certainty to calculate which of them, dur- 
ing life, should absorb most oxygen by chemical 
action when the influence of light is withdraw^n. 

The leaves and green parts of all plants contain- 
ing volatile oils or volatile constituents in general, 
which change into resin by the absorption of oxygen, 
should absorb more than other parts which are free 
from such substances. Those leaves, also, which 
contain either the constituents of nut-galls, or com- 



INFLUENCE OF THE SHADE ON PLANTS. 51 

pounds in whicL nitrogen is present, ought to absorb 
more oxygen tli m those which do not contain such 
matters. The correctness of these inferences has 
been distinctly proved by the observations of De 
Saussure ; for, whilst the tasteless leaves of the 
Agave americana absorb only 0*3 of their volume of 
oxygen in the dark, during 24 hours, the leaves of 
the Pinus Abies, which contain volatile and resinous 
oils, absorb 10 times, those of the Qiiercus Robiir 
containing tannic acid 14 times, and the balmy leaves 
of the Populus alba 21 times that quantity. This 
chemical action is shown very plainly, also, in the 
leaves of the Cotyledon cali/cinum, the Cacalia 
Jicoides, and others ; for they are sour like sorrel in 
the morning, tasteless at noon, and bitter in the 
evening. The formation of acids is effected during 
the night by a true process of oxidation : these are 
deprived of their acid properties during the day and 
evening, and are changed by separation of a part of 
their oxygen into compounds containing oxygen and 
hydrogen, either in the same proportions as in water, 
or even with an excess of hydrogen, which is the 
composition of all tasteless and bitter substances. 

Indeed the quantity of oxygen absorbed could be 
estimated pretty nearly by the different periods 
which the green leaves of plants require to undergo 
alteration in color, by the influence of the atmosphere. 
Those which continue longest green will abstract 
less oxygen from the air in an equal space of time, 
than those, the constituent parts of which suffer a 
more rapid change. It is found, for example, that 
the leaves of the Ilex aquifoliiim, distinguished by 
the durability of their color, absorb only 0-86 of 
their volume of oxygen gas in the same time that 
the leaves of the poplar absorb 8, and those of the 
beech 9| times their volume ; both the beech and 
poplar being remarkable for the rapidity and ease 
with which the color of their leaves changes. 

When the green leaves of the poplar, the beech, 
the oak, or the holly, are dried under the air-pump, 



52 OF THE ASSIMILATION OF CARBON. 

with exclusion of light, then moistened with water, 
and placed under a glass globe filled with oxygen, 
they are found to absorb that gas in proportion as 
they change in color. The chemical nature of this 
process is thus completely established. The diminu- 
tion of the gas which occurs can only be owing to 
the union of a large proportion of oxygen with those 
substances which are already in the state of oxides, 
or to the oxidation of the hydrogen in those vege- 
table compounds which contain it in excess. The 
fallen brown or yellow leaves of the oak contain no 
longer tannin, and those of the poplar no balsamic 
constituents. 

The property which green leaves possess of ab- 
sorbing oxygen belongs also to fresh wood, whether 
taken from a twig or from the interior of the trunk 
of a tree. When fine chips of such wood are placed 
in a moist condition under a jar filled with oxygen, 
the gas is seen to diminish in volume. But wood, 
dried by exposure to the atmosphere and then moist- 
ened, converts the oxygen into carbonic acid, with- 
out change of volume ; fresh wood, therefore, absorbs 
most oxygen. 

MM. Petersen and Schodler have shown, by the 
careful elementary analysis of 24 different kinds of 
wood, that they contain carbon and the elements of 
water, with the addition of a certain quantity of 
hydrogen. Oak wood, recently taken from the tree, 
and dried at 100^^ C. (212° F.), contains 49-432 
carbon, 6-069 hydrogen, and 44-499 oxygen. 

The proportion of hydrogen which is necessary to 
combine with 44-498 oxygen in order to form water, 
is g of this quantity, namely, 5-56 ; it is evident, 
therefore, that oak wood contains i more hydrogen 
than corresponds to this proportion. In Pimis 
Lariv, P. Abies, and P. picea, the excess of hydro- 
gen amounts to i, and in Tilia europcBa to \. The 
quantity of hydrogen stands in some relation to the 
specific weight of the wood ; the lighter kinds of 
vood contain more of it than the heavier. In ebony 



EVOLUTION OF CARBONIC ACID DURING THE NIGHT. 53 

wood (^Diospyros Ebenutn) the oxygen and hydrogen 
are in exactly the same proportion as in water. 

The difference between the composition of the 
varieties of wood, and that of simple woody fibre, 
depends, unquestionably, upon the presence of con- 
stituents, in part soluble, and in part insoluble, such 
as resin and other matters, which contain a large 
proportion of hydrogen : the hydrogen of such sub- 
stances being in the analysis of the various woods 
superadded to that of the true woody fibre. 

It has previously been mentioned that mouldering 
oak wood contains carbon and the elements of water, 
without any excess of hydrogen. But the propor- 
tions of its constituents must necessarily have been 
different, if the volume of the air had not changed 
during its decay, because the proportion of hydrogen 
in those component substances of the wood which 
contained it in excess is here diminished, and this 
diminution could only be effected by an absorption 
of oxygen, and consequent formation of water. 

Most vegetable physiologists have connected the 
emission of carbonic acid during the night with the 
absorption of oxygen from the atmosphere, and have 
considered these actions as a true process of respi- 
ration in plants, similar to that of animals, and like 
it, having for its result the separation of carbon 
from some of their constituents. This opinion has 
a very weak and unstable foundation. 

The carbonic acid, which has been absorbed by 
the leaves and by the roots, together with water, 
ceases to be decomposed on the departure of day- 
light ; it is dissolved in the juices which pervade 
all parts of the plant, and escapes every moment 
through the leaves in quantity corresponding to that 
of the water which evaporates. 

A soil in which plants vegetate vigorously, con- 
tains a certain quantity of moisture which is indis- 
pensably necessary to their existence. Carbonic 
acid, likewise, is always present in such a soil, 
whether it has been abstracted from the air or has 
5* 



54 OF THE ASSIMILATION OF CARBON. 

been generated by the decay of vegetable matter. 
Rain and well water, and also that from other 
sources, invariably contains carbonic acid. — Plants 
during their life constantly possess the power of 
absorbing by their roots moisture, and, along with 
it, air and carbonic acid. Is it, therefore, surprising 
that the carbonic acid should be returned unchanged 
to the atmosphere, along with water, when light 
(the cause of the fixation of its carbon) is absent? 

Neither this emission of carbonic acid nor the 
absorption of oxygen has any connexion with the 
process of assimilation ; nor have they the slightest 
relation to one another ; the one is a purely me- 
chanical, the other a purely chemical process. A 
cotton wick, inclosed in a lamp, which contains a 
liquid saturated with carbonic acid, acts exactly in 
the same manner as a living plant in the night. 
Water and carbonic acid are sucked up by capillary 
attraction, and both evaporate from the exterior part 
of the wick. 

Plants which live in a soil containing humus exhale 
much more carbonic acid during the night than those 
which grow in dry situations ; they also yield more 
in rainy than, in dry weather. These facts point out 
to us the cause of the numerous contradictory 
observations, which have been made with respect to 
the change impressed upon the air by living plants, 
both in darkness and in common daylight, but 
which are unworthy of consideration, as they do not 
assist in the solution of the main question. 

There are other facts which prove in a decisive 
manner that plants yield more oxygen to the atmo- 
sphere than they extract from it ; these proofs, 
however, are to be drawn with certainty only from 
plants which live under water. 

When pools and ditches, the bottoms of which 
are covered with growing plants, freeze upon their 
surface in winter, so that the water is completely 
excluded from the atmosphere by a clear stratum of 
ice, small bubbles of gas are observed to escape, con- 



NEGLECT OF CHEMISTRY BY BOTANISTS. 55 

tinually, during the day, from the points of the leaves 
and twigs. These bubbles are seen most distinctly 
when the rays of the sun fall upon the ice ; they are 
very small at first, but collect under the ice and form 
larger bubbles. They consist of pure oxygen gas. 
Neither during the night, nor during the day when 
the sun does not shine, are they observed to diminish 
in quantity. The source of this oxygen is the car- 
bonic acid dissolved in the water, which is absorbed 
by the plants, but is again supplied to the water, by 
the decay of vegetable substances contained in the 
soil. If these plants absorb oxygen during the night, 
it can be in no greater quantity than that which the 
surrounding water holds in solution, for the gas, 
which has been exhaled, is not again absorbed. The 
action of water-plants cannot be supposed to form 
an exception to a great law of nature, and the less 
so, as the different action of aerial plants upon the 
atmosphere is very easily explained. 

The opinion is not new, that the carbonic acid of 
the air serves for the nutriment of plants, and that 
its carbon is assimilated by them ; it has been ad- 
mitted, defended, and argued for, by the soundest 
and most intelligent natural philosophers, namely, by 
Priestley, Sennebier, De Saussure, and even by In- 
genhouss himself. There scarcely exists a theory 
in natural science, in favor of which there are more 
clear and decisive arguments. How, then, are we 
to account for its not being received in its full extent 
by most other physiologists, for its being even dis- 
puted by many, and considered by a few as quite 
refuted ? 

All this is due to two causes, which we shall now 
consider. 

One is, that in botany the talent and labor of in- 
quirers has been wholly spent in the examination of 
form and structure : chemistry and physics have not 
been allowed to sit in council upon the explanation 
of the most simple processes ; their experience and 
their laws have not been employed, though the most 



56 OF THE ASSIMILATION OF CAKBON. 

powerful means of help in the acquirement of true 
knowledge. They have not been used, because their 
study has been neglected. 

All discoveries in physics and in chemistry, all 
explanations of chemists, must remain without fruit 
and useless, because, even to the great leaders in 
physiology, carbonic acid, ammonia, acids, and bases, 
are sounds without meaning, \vords without sense, 
terms of an unknown language, which awaken no 
thoughts and no associations. They treat these 
sciences like the vulgar, who despise a foreign lite- 
rature in exact proportion to their ignorance of it ; 
since even when they have had some acquaintance 
with them, they have not understood their spirit and 
application. 

Physiologists reject the aid of chemistry in their 
inquiry into the secrets of vitality, although it alone 
could guide them in the true path; they reject chem- 
istry, because in its pursuit of knowledge it destroys 
the subjects of its investigation ; but they forget 
that the knife of the anatomist must dismember the 
body, and destroy its organs, if an account is to be 
given of their form, structure, and functions. 

When pure potato starch is dissolved in nitric 
acid, a ring of the finest wax remains. What can 
be opposed to the conclusion of the chemist, that 
each grain of starch consists of concentric layers of 
wax and amylin, which thus mutually protect each 
other against the action of water and ether? Can 
results of this kind, which illustrate so completely 
both the nature and properties of bodies, be attained 
by the microscope? Is it possible to make the glu- 
ten in a piece of bread visible in all its connexions 
and ramifications? It is impossible by means of in- 
struments ; but if the piece of bread is placed in a 
lukewarm decoction of malt, the starch, and the sub- 
stance called dextrine,* are seen to dissolve like 

* According to Raspail, starch consists of vesicles inclosing within 
them a fluid resembling gum. Starch maj' be put in cold water with- 
out being dissolved ; but, when placed in hot water, these spherules 



OBJECT OF EXPERIMENTS IN PHYSIOLOGY. 57 

sugar in water, and, at last, nothing remains except 
the gluten, in the form of a spongy mass, the minute 
pores of which can be seen only by a microscope. 

Chemistry offers innumerable resources of this kind 
which are of the greatest use in an inquiry into the 
nature of the organs of plants ; but they are not used, 
because the need of them is not felt. The most im- 
portant organs of animals and their functions are 
known, although they may not be visible to the 
naked eye. But in vegetable physiology, a leaf is in 
every case regarded merely as a leaf, notwithstand- 
ing that leaves generating oil of turpentine or oil of 
lemons must possess a different nature from those 
in which oxalic acid is formed. Vitality, in its pe- 
culiar operations, makes use of a special apparatus 
for each function of an organ. A rose-twig engraft- 
ed upon a lemon-tree does not bring forth lemons, 
but roses. Vegetable physiologists in the study of 
their science have not directed their attention to that 
part of it which is most worthy of investigation. 

The second cause of the incredulity with which 
physiologists view the theory of the nutrition of 
plants by the carbonic acid of the atmosphere is, 
that the art of experimenting is not known in physi- 
ology, it being an art which can be learned accurate- 
ly only in the chemical laboratory. Nature speaks 
to us in a peculiar language, in the language of phe- 
nomena; she answers at all times the questions which 
are put to her ; and such questions are experiments. 
An experiment is the expression of a thought : we 
are near the truth when the phenomenon elicited by 
the experiment corresponds to the thought ; while 

burst, and allow the escape of the liquid. This liquid is the dextrine 
of Biot, so called because it possesses the property of turning the plane 
of the polarization of light to the right hand. It is white, insipid, trans- 
parent in thin flakes and gummy. At 230° F. it becomes brown and 
acquires the flavor of toasted bread. It is much employed by the French 
pastry cooks and confectioners ; being reduced to powder it may be in- 
troduced into all kinds of pastries, bread, chocolate, &c. For its prep- 
aration, &c., see Ure's Dictionary of Arls and Manufactures, a.nd Web- 
ster's Chemistry, 510. 



58 OF THE ASSIMILATION OF CARBON. 

the opposite result shows that the question was false- 
ly stated, and that the conception was erroneous. 

The critical repetition of another's experiments 
must be viewed as a criticism of his opinions ; if the 
result of the criticism be merely negative, if it do not 
suggest more correct ideas in the place of those 
which it is intended to refute, it should be disre- 
garded ; because the worse experimenter the critic 
is, the greater will be the discrepancy between the 
results he obtains and the views proposed by the 
other. 

It is too much forgotten by physiologists, that their 
duty really is not to refute the experiments of others, 
nor to show that they are erroneous, but to discover 
truth, and that alone. It is startling, when we re- 
flect that all the time and energy of a multitude of 
persons of genius, talent, and knowledge, are ex- 
pended in endeavors to demonstrate each other's 
errors. 

The question whether carbonic acid is the food of 
plants or not has been made the subject of experi- 
ments with perfect zeal and good faith ; the results 
have been opposed to that view. But how was the 
inquiry instituted? 

The seeds of balsamines, beans, cresses, and 
gourds, were sown in pure Carrara marble, and 
sprinkled with water containing carbonic acid. The 
seeds sprang, but the plants did not attain to the 
development of the third small leaf. In other cases, 
they allowed the water to penetrate the marble from 
below, yet, in spite of this, they died. It is w^orthy 
of observation, that they lived longer with pure dis- 
tilled water than with that impregnated with carbon- 
ic acid ; but still, in this case also, they eventually 
perished. Other experimenters sowed seeds of plants 
in flowers of sulphur and sulphate of barytes, and 
tried to nourish them with carbonic acid, but without 
success. 

Such experiments have been considered as positive 
proofs, that carbonic acid will not nourish plants ; 



CONDITIONS ESSENTIAL TO NUTRITION. 59 

but the manner in which they were instituted is op- 
posed to all rules of philosophical inquiry, and to all 
the laws of chemistry. 

Many conditions are necessary for the life of plants; 
those of each genus require special conditions ; and 
should but one of these be wanting, although the 
rest be supplied, the plants will not be brought to 
maturity. The organs of a plant, as well as those 
of an animal, contain substances of the most differ- 
ent kinds ; some are formed solely of carbon and the 
elements of water, others contain nitrogen, and in 
all plants we find metallic oxides in the state of salts. 
The food which can serve for the production of all 
the organs of a plant, must necessarily contain all its 
elements. These most essential of all the chemical 
qualities of nutriment may be united in one substance, 
or they may exist separately in several; in which 
case, the one contains what is wanting in the other. 
Dogs die although fed with jelly, a substance which 
contains nitrogen ; they cannot live upon white bread, 
sugar, or starch, if these are given as food, to the 
exclusion of all other substances. Can it be con- 
cluded from this, that these substances contain no 
elements suited for assimilation 1 Certainly not. 

Vitality is the power which each organ possesses 
of constantly reproducing itself; for this it requires 
a supply of substances which contain the constitu- 
ent elements of its own substance, and are capable 
of undergoing transformation. All the organs to- 
gether cannot generate a single element, carbon, ni- 
trogen, or a metallic oxide. 

When the quantity of the food is too great, or is 
not capable of undergoing the necessary transform- 
ation, or exerts any peculiar chemical action, the or- 
gan itself is subjected to a change : all poisons act 
in this manner. The most nutritious substances may 
cause death. In experiments such as those describ- 
ed above, every condition of nutrition should be con- 
sidered. Besides those matters which form their 
principal constituent parts, both animals and plants 



60 OF THE ASSIMILATION OF CARBON. 

require others, the peculiar functions of which are 
unknown. These are inorganic substances, such as 
common salt, the total want of which is in animals 
inevitably productive of death. Plants, for the same 
reason, cannot live unless supplied with certain me- 
tallic compounds. 

If we knew with certainty that there existed a 
substance capable, alone, of nourishing a plant and 
of bringing it to maturity, we might be led to a 
knowledge of the conditions necessary to the life of 
all plants, by studying its characters and composi- 
tion. If humus were such a substance, it would 
have precisely the same value as the only single food 
which nature has produced for animal organization, 
namely, milk. (Prout.) The constituents of milk are 
cheese or caseine, a compound containing nitrogen 
in large proportion ; butter, in which hydrogen 
abounds ; and sugar of milk, a substance with a 
large quantity of hydrogen and oxygen in the same 
proportion as in water. It also contains in solution, 
lactate of soda, phosphate of lime, and common salt ; 
and a peculiar aromatic product exists in the butter, 
called butyric acid. The knowledge of the compo- 
sition of milk is a key to the conditions necessary 
for the purposes of nutrition of all animals. 

All substances which are adequate to the nourish- 
ment of animals contain those materials united, 
though not always in the same form ; nor can any 
one be wanting for a certain space of time, without 
a marked effect on the health being produced. The 
employment of a substance as food presupposes a 
knowledge of its capacity of assimilation, and of the 
conditions under which this takes place. 

A carnivorous animal dies in the vacuum of an 
air-pump, even though supplied with a superabun- 
dance of food ; it dies in the air, if the demands of 
its stomach are not satisfied; and it dies in pure 
oxygen gas, however lavishly nourishment be given 
to it. Is it hence to be concluded, that neither flesh, 



CONDITIONS ESSENTIAL TO NUTRITION. 61 

nor air, nor oxygen, is fitted to support life 1 Cer- 
tainly not. 

From the pedestal of the Trajan column at Rome 
we might chisel out each single piece of stone, if 
upon the extraction of the second we replaced the 
first. But could we conclude from this that the col- 
umn was suspended in the air, and not supported by 
a single piece of its foundation ? Assuredly not. 
Yet the strongest proof would have been given that 
each portion of the pedestal could be removed, with- 
out the downfall of the column. 

Animal and vegetable physiologists, however, come 
to such conclusions with respect to the process of 
assimilation. They institute experiments, without 
being acquainted with the circumstances necessary 
for the continuance of life, — with the qualities and 
proper nutriment of the animal or plant on which 
they operate, — or with the nature and chemical con- 
stitution of its organs. These experiments are con- 
sidered by them as convincing proofs, whilst they 
are fitted only to awaken pity. 

Is it possible to bring a plant to maturity by means 
of carbonic acid and water, without the aid of some 
substance containing nitrogen, which is an essential 
constituent of the sap, and indispensable for its pro- 
duction ? Must the plant not die, however abundant 
the supply of carbonic acid may be, as soon as the 
first small leaves have exhausted the nitrogen con- 
tained in the seeds ? 

Can a plant be expected to grow in Carrara mar- 
ble, even when an azotized substance is supplied to 
it, if the marble be sprinkled with an aqueous solu- 
tion of carbonic acid, which dissolves the lime and 
forms bicarbonate of lime 1 A plant of the family of 
the Plumbagme(S, upon the leaves of which fine 
hornlike, or scaly processes of crystallized carbonate 
of lime are formed, might perhaps attain maturity 
under such circumstances ; but these experiments 
are only sufficient to prove, that cresses, gourds, and 
balsamines, cannot be nourished by bicarbonate of 
6 



62 OF THE ASSIMILATION OF CARBON. 

lime, in the absence of matter containing nitrogen. 
We may, indeed, conclude, that the salt of lime acts 
as a poison, since the development of plants will ad- 
vance further in pure water, when lime and carbonic 
acid are not used. 

Moist flowers of sulphur attract oxygen from the 
atmosphere, and become acid. Is it possible that a 
plant can grow and flourish in presence of free sul- 
phuric acid, with no other nourishment than carbonic 
acid ? It is true, the quantity of sulphuric acid 
formed thus in hours, or in days, may be small, but 
the property of each particle of the sulphur to absorb 
oxygen and retain it, is present every moment. 

When it is known that plants require moisture, 
carbonic acid, and air, should we choose, as the soil 
for experiments on their growth, sulphate of barytes, 
which, from its nature and specific gravity, com- 
pletely prevents the access of air. 

All these experiments are valueless for the deci- 
sion of any question. It is absurd to take for them 
any soil, at mere hazard, so long as we are ignorant 
of the functions performed in plants by those inor- 
ganic substances which are apparently foreign to them. 
It is quite impossible to mature a plant of the fam- 
ily of the GraniinecB, or of the EquisetacecB, the solid 
framework of which contains silicate of potash, with- 
out silicic acid and potash, or a plant of the genus 
Oxalis without potash, or saline plants such as the 
saltworts {^Salsola and Salicornia) without chloride 
of sodium, or at least some salt of similar proper- 
ties. All seeds of the GraminecB contain phosphate 
of magnesia; the solid parts of the roots of the 
alihcBa contain more phosphate of lime than woody 
fibre. Are these substances merely accidentally 
present ? A plant should not be chosen for experi- 
ment, when the matter which it requires for its 
assimilation is not well known. 

What value, now, can be attached to experiments 
in which all those matters which a plant requires in 
the process of assimilation, besides its mere nutri- 



ON THE ORIGIN AND ACTION OF HUMUS. 63 

ment, have been excluded with the greatest care ? 
Can the laws of life be investigated in an organized 
being which is diseased or dying 1 

The mere observation of a wood or meadow is 
infinitely better adapted to decide so simple a ques- 
tion than all the trivial experiments under a glass 
globe ; the only difference is, that instead of one 
plant there are thousands. When we are acquainted 
with the nature of a single cubic inch of their soil, 
and know the composition of the air and rain-water, 
we are in possession of all the conditions necessary 
to their life. The source of the different elements 
entering into the composition of plants cannot 
possibly escape us, if we know in what form they 
take up their nourishment, and compare its composi- 
tion with that of the vep:etable substances which 
compose their structure. 

All these questions will now be examined and 
discussed. It has been already shown, that the 
carbon of plants is derived from the atmosphere : it 
still remains for us to inquire, what power is exerted 
on vegetation by the humus of the soil and the 
inorganic constituents of plants, and also to trace 
the sources of their nitrogen. 



CHAPTER III. 

ON THE ORIGIN AND ACTION OF HUMUS. 

It will be shown in the second part of this work, 
that all plants and vegetable structures undergo two 
processes of decomposition after death. One of 
these is named fermentation ; the other, putrefaction, 
decay, or eremacausis* 

* The word eremacausis was proposed by the author some time since, 
in order to explain the true nature of decay; it is compounded from 
i]ijfiia, by degrees, and i^avaic, hurnincr. — Tr. 

Eremacausis is the act of gradual combination of the combustible 



64 ox THE ORIGIN AND ACTION OF HUMUS. 

It will likewise be shown, that decay is a slow 
process of combustion, — a process, therefore, in 
which the combustible parts of a plant unite with 
the oxygen of the atmosphere. 

The decay of woody fibre (the principal constit- 
uent of all plants) is accompanied by a phenomenon 
of a peculiar kind. This substance, in contact with 
air or oxygen gas, converts the latter into an equal 
volume of carbonic acid, and its decay ceases upon 
the disappearance of the oxygen. If the carbonic 
acid is removed, and oxygen replaced, its decay 
recommences, that is, it again converts oxygen into 
carbonic acid. Woody fibre consists of carbon and 
the elements of water ; and if we judge only from 
the products formed during its decomposition, and 
from those formed by pure charcoal, burned at a high 
temperature, w^e might conclude that the causes 
were the same in both: the decay of woody fibre 
proceeds, therefore, as if no hydrogen or oxygen 
entered into its composition.* 

A very long time is required for the completion 
of this process of combustion, and the presence of 
water is necessary for its maintenance ; alkalies 
promote it, but acids retard it; all antiseptic sub- 



elements of a body with the oxygen of the air; a slow combustion or 
oxidation. 

The conversion of wood into humus, the formation of acetic acid 
out of alcohol, nitrification, and numerous other processes, are of this 
nature. Vegetable juices of every kind, parts of animal and vegetable 
substances, moist sawdust, blood, &c., cannot be e.Kposed to the air, 
without suffering immediately a progressive change of color and prop- 
erties, during which oxygen is absorbed. These changes do not take 
place when water is excluded, or when the substances are exposed to 
the temperature of 32'-', and diiferent bodies require different degrees 
of heat, in order to effect the absorption of oxygen, and, consequently, 
their eremacausis. The property of suffering this change is possessed 
in tiie highest degree by substances which contain nitrogen. — Liebig. 
Org. Chem. Part 2d. 

* In the Appendix to the Third Report of the Agriculture of Massa- 
fhuscUs, 1840, Dr. S. L. Dana adduces the following example, to show 
that even a moist plant will not decay, if air is excluded. A piece of 
a white birch tree was taken from a deptli of twenty-five feet below 
the surface, in Lowell. "It must have been inhumed there probably 
before the creation of man, yet this most perishable of all wood is 
nearly as sound as if cut from the forest last fall." 



IT EVOLVES CARBONIC ACID. 65 

stances, such as sulphurous acid, the mercurial salts, 
empyreumatic oils, &c., cause its complete cessation. 

Woody fibre in a state of decay is the substance 
called humus.* 

The property of woody fibre to convert surround- 
ing oxygen gas into carbonic acid diminishes in 
proportion as its decay advances, and at last a cer- 
tain quantity of a brown coaly-looking substance 
remains, in which this property is entirely wanting. 
This substance is called mould; it is the product of 
the complete decay of woody fibre. Mould consti- 
tutes the principal part of all the strata of brown 
coal and peat. 

Humus acts in the same manner in a soil permeable 
to air as in the air itself; it is a continued source of 
carbonic acid, which it emits very slowly. An atmo- 
sphere of carbonic acid, formed at the expense of 
the oxygen of the air, surrounds every particle of 
decaying humus. The cultivation of land, by tilling 
and loosening the soil, causes a free and unob- 
structed access of air. An atmosphere of carbonic 
acid is therefore contained in every fertile soil, and 
is the first and most important food for the young 
plants which grow in it. 

In spring, when those organs of plants are absent 
which nature has appointed for the assumption of 
nourishment from the atmosphere, the component 
substance of the seeds is 'exclusively employed in 
the formation of the roots. Each new radicle fibril 
which a plant acquires may be regarded as consti- 
tuting at the same time a mouth, a lung, and a 
stomach. The roots perform the functions of the 
leaves from the first moment of their formation : 
they extract from the soil their proper nutriment, 
namely, the carbonic acid generated by the humus. 

By loosening the soil which surrounds young 
plants, we favor the access of air, and the formation 

* The humic acid of chemists is a product of the decomposition of 
humus by alkalies; it does not exist in the humus of vegetable physi- 
ologists. — L. 

6* 



66 ON THE ORIGIN AND ACTION OF HUMUS. 

of carbonic acid ; and, on the other hand, the quan- 
tity of their food is diminished by every difficulty 
which opposes the renewal of air. A plant itself 
effects this change of air at a certain period of its 
growth. The carbonic acid, which protects the 
undecayed humus from further change, is absorbed 
and taken away by the fine fibres of the roots, and 
by the roots themselves ; this is replaced by atmo- 
spheric air, by which process the decay is renewed, 
and a fresh portion of carbonic acid formed. A 
plant at this time receives its food both by the roots 
and by the organs above ground, and advances 
rapidly to maturity. 

When a plant is quite matured, and when the 
organs by which it obtains food from the atmosphere 
are formed, the carbonic acid of the soil is no fur- 
ther required. 

Deficiency of moisture in the soil, or its complete 
dryness, does not now check the growth of a plant, 
provided it receives from the dew and the atmosphere 
as much as is requisite for the process of assimila- 
tion. During the heat of summer it derives its 
carbon exclusively from the atmosphere. 

We do not know what height and strength nature 
has allotted to plants ; we are acquainted only with 
the size which they usually attain. Oaks are shown, 
both in London and Amsterdam, as remarkable curi- 
osities, which have been reared by Chinese gardeners, 
and are only one foot and a half in height, although 
their trunks, barks, leaves, branches, and whole 
habitus, evince a venerable age. The small parsnep 
grown at Teltow,* when placed in a soil which yields 
as much nourishment as it can take up, increases to 
several pounds in weight. 

The size of a plant is proportional to the surface 
of tJte organs which are destined to convey food to it. 

* Teltow is a village near Berlin, where small parsneps are culti- 
vated in a sandy soil ; they are much esteemed, and weigli rarely 
above one ounce. — L. 



GROWTH OF PLANTS. 67 

A plant gains another mouth and stomach with every 
new fibre of root, and every new leaf. 

The power which roots possess of taking up nour- 
ishment does not cease as long as nutriment is 
present. When the food of a plant is in greater 
quantity than its organs require for their own perfect 
development, the superfluous nutriment is not re- 
turned to the soil, but is employed in the formation 
of new organs. At the side of a cell, already formed, 
another cell arises ; at the side of a twig and leaf, 
a new twig and a new leaf are developed. These 
new parts could not have been formed had there not 
been an excess of nourishment. The sugrar and 
mucilage produced in the seeds, form the nutriment 
of the young plants, and disappear during the de- 
velopment of the buds, green sprouts, and leaves. 

The power of absorbing nutriment from the atmo- 
sphere, with which the leaves of plants are endowed, 
being proportionate to the extent of their surface, 
every increase in the size and number of these parts 
is necessarily attended with an increase of nutritive 
power, and a consequent further development of new 
leaves and branches. Leaves, twigs, and branches, 
when completely matured, as they do not become 
larger, do not need food for their support. For 
their existence as organs, they require only the 
means necessary for the performance of the special 
functions to which they are destined by nature; they 
do not exist on their own account. 

We know that the functions of the leaves and 
other green parts of plants are to absorb carbonic 
acid, and with the aid of light and moisture, to 
appropriate its carbon. These processes are contin- 
ually in operation ; they commence with the first 
formation of the leaves, and do not cease with their 
perfect development. But the new products arising 
from this continued assimilation are no longer em- 
ployed by the perfect leaves in their own increase : 
they serve for the formation of woody fibre, and all 
the solid matters of similar composition. The leaves 



68 ON THE ORIGIN AND ACTION OF HUIMUS. 

now produce sugar, amylin or starch, and acids, 
which were previously formed by the roots, when 
they were necessary for the development of the stem, 
buds, leaves, and branches of the plant. 

The organs of assimilation, at this period of their 
life, receive more nourishment from the atmosphere 
than they employ in their own sustenance ; and when 
the formation of the woody substance has advanced 
to a certain extent, the expenditure of the nutriment, 
the supply of w^hich still remains the same, takes a 
new direction, and blossoms are produced. The 
functions of the leaves of most plants cease upon 
the ripening of their fruit, because the products of 
their action are no longer needed. They now yield 
to the chemical influence of the oxygen of the air, 
generally suff"er a change in color, and fall off. 

A peculiar " transformation " of the matters con- 
tained in all plants takes place in the period between 
blossoming and the ripening of the fruit; new com- 
pounds are produced, which furnish constituents of 
the blossoms, fruit, and seed. An organic chemical 
"transformation" is the separation of the elements 
of one or several combinations, and their reunion 
into two or several others, which contain the same 
number of elements, either grouped in another man- 
ner, or in different proportions. Of two compounds 
formed in consequence of such a change, one remains 
as a component part of the blossom or fruit, while 
the other is separated by the roots in the form of 
excrementitious matter. No process of nutrition 
can be conceived to subsist in animals or vegetables, 
without a separation of effete matters. We know, 
indeed, that an organized body cannot generate 
substances, but can only change the mode of their 
combination, and that its sustenance and reproduc- 
tion depend upon the chemical transformation of the 
matters which are employed as its nutriment, and 
which contain its own constituent elements. 

Whatever we regard as the cause of these trans- 
formations, whether the Vital Principle, Increase of 



TRANSFORMATIONS OF ORGANIC SUBST.^NCES. 69 

Temperature, Light, Galvanism, or any other influ- 
ence, the act of transformation is a purely chemical 
process. Combination and Decomposition can take 
place only when the elements are disposed to these 
changes. That which chemists name affinity indi- 
cates only the degree in which they possess this 
disposition. It will be shown, when considering the 
processes of fermentation and putrefaction, that every 
disturbance of the mutual attraction subsisting be- 
tween the elements of a body gives rise to a trans- 
formation. The elements arrange themselves accord- 
ing to the degrees of their reciprocal attraction into 
new combinations, which are incapable of further 
change under the same conditions. 

The products of these transformations vary with 
their causes, that is, with the different conditions on 
which their production depended ; and are as innu- 
merable as these conditions themselves. The chem- 
ical character of an acid, for example, is its unceas- 
ing disposition to saturation by means of a base;* 
this disposition differs in intensity in different acids; 
but when it is satisfied, the acid character entirely 
disappears. The chemical character of a base is 
exactly the reverse of this, but both an acid and a 
base, notwithstanding the great difference in their 



* Liebig applies the term base to compounds which unite with acids 
and neutralize their characters. The product is a salt. When the 
characters of both acids and bases disappear the compound is neutral. 

Some acids contain oxygen, others hydrogen. Several metals form 
acids with oxygen ; but the greater number of metallic oxides, are, in 
their relations, totally different from the acids. They form compounds, 
which, for the most part, are insoluble in water ; those soluble in water 
have an alkaline taste, and possess the property of restoring the blue 
color of vegetables, which have been reddened by acids. Tliese also 
change many vegetable T/elloios to red or brown. The alkalies are 
soluble bases. Many salts redden vegetable blues, and others again 
restore the blue color of vegetables reddened by acids; in the first 
instance, the salt possesses an acid, and in the latter an alkaline, 
reaction. 

A simple body, which is capable of forming either an acid or a base, 
is termed a radical; a compound radical consists of two or three simple 
radicals, and comports itself in a similar manner to the simple radicals; 
that is, it is capable of forming acids and bases. 



70 ON THE ORIGIN AND ACTION OF HUMUS. 

properties, effect, in most cases, the same kind of 
transformations. 

Hydrocyanic acid {^prussic acid)* and water con- 
tain the elements of carbonic acid, ammonia^ urea, 
cyanuric acid, cyanilic acid, oxalic acid, formic acid, 
melam, ammelin, melamin, azulmin, meUo7i, hydro- 
mellonic acid, allantoin, 6^c.-\ It is well known, that 
all these very different substances can be obtained 

* Cyanogen is considered by Liebig as a compound base, and as 
such uniting witli oxygen, hydrogen, and most other nonmetallic 
elements and with the metals. Cyanogen gas, or bicarburet of nitro- 
gen, is a compound of nitrogen and carbon, and was named from its 
affording a blue color and being an ingredient of Prussian blue. For 
the method of obtainino- it, &c., see Webster's Ckemistrij, Sd edition, 
p. 219. 

With hydrogen it constitutes hydrocyanic acid. 

f Carbonic acid is a gaseous compound of 1 equivalent of carbon, 
and 2 equivalents of oxygen, represented thus, C -f- 20 or ij, the two 
dots denoting the two of oxygen. 

Ammonia consists of 3 equivalents of hydrogen, and 1 equivalent of 
nitrogen, represented thus, N -j- 3H, or NH3. 

Urea contains the elements of cyanate of ammonia (NH4 O -(- C4 NO), 
and exists in urine, from which it is obtained in colorless, transparent 
crystals. 

Cyanuric acid is a product of the decomposition of chloride of cyan- 
ogen, of urea, &c. It is called a tribasic acid, and its hydrate is thus 
represented, Cys O3 -\- 3HO. 

Oxalic acid is a solid acid obtained from several plants, particularly 
of the genera oxalis, rumex, &c. combined with potassa in roots, and 
with lime in several kinds of lichens. Oxalate of lime is found in 
urinary calculi. It is represented thus, i!CO 4- O (2 equivalents of 
carbonic oxide -(- I oxvgen). The so-called Essential salt of lemons is 
a binoxalate of potash. It is poisonous. 

Formic acid, obtained from ants, hence its name. It is now obtained 
from sugar and other vegetable substances. Represented by C^ HO3. 

Melam is a compound of C12 Nn Hg; it is a white powder insoluble 
in water, and, by the action of acids, converted into cyanuric acid and 
ammonia. 

Ammelin, a saline base, represented thus, Ce N3 H5 O2, a product of 
the decomposition of melam b}'^ acids and alkalies. 

Melamin, a saline base, product of the decomposition of melam, 
Ce Ne Hg. Decomposed by acids into ammonia and ammelid or 
ammelin. 

Jlzubnen, the base of azulmic acid, obtained by the decomposition 
of cyanogen. The acid is Cs H4 N4 O4. 

Mellon, a compound base, a yellow powder. Decomposed into 3 
volumes cyanogen and 1 volume nitrogen gas. Ce N4. 

Uijdromellonic acid is Cs N4 -(- H. 

Mtantoinc or allantoic acid occurs in the allantoic fluid of the cow ; 
it is formed when uric acid is boiled in water with peroxide of lead. 
It is Ci H3 N2 O3 or 2Cy + 3HO. 



TRANSFORMATIONS OF ORGANIC SUBSTANCES. 71 

from hydrocyanic acid and the elements of water, 
by various chemical transformations. 

The whole process of nutrition may be understood 
by the consideration of one of these transformations. 

Hydrocyanic acid and water, for example, when 
brought into contact with muriatic acid, are decom- 
posed into formic acid and ammonia; both of these 
products of decomposition contain the elements of 
hydrocyanic acid and water, although in another 
form, and arranged in a different order. The change 
results from the strong disposition or struggle of 
muriatic acid to undergo saturation, in consequence 
of which the hydrocyanic acid and water suffer 
mutual decomposition. The nitrogen of the hydro- 
cyanic acid and the hydrogen of the water unite 
together and form a base, ammonia, with which the 
acid unites ; the chemical characters of the acid 
being at the same time lost, because its desire for 
saturation is satisfied by its uniting with ammonia. 
Ammonia itself was not previously present, but only 
its elements, and the power to form it. The simul- 
taneous decomposition of hydrocyanic acid and wa- 
ter in this instance does not take place in conse- 
quence of the chemical affinity of muriatic acid for 
ammonia, since hydrocyanic acid and water contain 
no ammonia. An affinity of one body for a second 
which is totally without the sphere of its attractions, 
or which, as far as it is concerned, does not exist, 
is quite inconceivable. The ammonia in this case is 
formed only on account of the existing attractive 
desire of the acid for saturation. Hence we may 
perceive how much these modes of decomposition, 
to which the name of transformations or metamorpho- 
ses has been especially applied, differ from the ordi- 
nary chemical decompositions. 

In consequence of the formation of ammonia, the 
other elements of hydrocyanic acid, namely, carbon 
and hydrogen, unite with the oxygen of the decom- 
posed water, and form formic acid, the elements of 
this substance with the power of combination being 



72 ON THE ORIGIN AND ACTION OF HUMUS. 

present. Formic acid here represents the excre- 
mentitious matters ; ammonia, the new substance, 
assimilated by an organ of a plant or animal. 

Each organ extracts from the food presented to it 
what it requires for its own sustenance; while the 
remaining elements, which are not assimilated, com- 
bine together and are separated as excrement. The 
excrementitious matters of one organ come in con- 
tact with another during their passage through the 
organism, and in consequence suffer new transfor- 
mations; the useless matters rejected by one organ 
containing the elements for the nutrition of a second 
and a third organ: but at last, being capable of no 
further transformations, they are separated from the 
system by the organs destined for that purpose. 
Each part of an organized being is fitted for its 
peculiar functions. A cubic inch of sulphuretted 
hydrogen introduced into the lungs would cause 
instant death, but it is formed, under a variety of 
circumstances, in the intestinal canal without any 
injurious effect.* 

In consequence of such transformations as we 
have described, excrements are formed of various 
composition; some of these contain carbon in ex- 
cess, others nitrogen, and others again hydrogen 
and oxygen. The kidneys, liver, and lungs, are or- 
gans of excretion ; the first separate from the body 
all those substances in which a large proportion of 
nitrogen is contained; the second, those with an 
excess of carbon; and the third, such as are com- 
posed principally of oxygen and hydrogen. Alco- 
hol, also, and the volatile oils which are incapable of 
being assimilated, are exhaled through the lungs, 
and not through the skin. 

Respiration must be regarded as a slow process 
of combustion or constant decomposition. If it be 
subject to the laws which regulate the processes 

* The danger of breathing carbonic acid gas is well known, but 
large quantities can be taken into the stomach with impunity and 
even benefit. 



TRANSFORMATIONS OF ORGANIC SUBSTANCES. 73 

of decomposition generally, the oxygen of the in- 
spired air cannot combine directly with the carbon 
of compounds of that element contained in the 
blood ; the hydrogen only can combine with the 
oxygen of the air, or undergo a higher degree of 
oxidation. Oxygen is absorbed without uniting with 
carbon ; and carbonic acid is disengaged, the car- 
bon and oxygen of w^hich must be derived from 
matters previously existing in the blood.* 

All superabundant nitrogen is eliminated from the 
body, as a liquid excrement, through the uriaary 
passages ; all solid substances, incapable of further 
transformation, pass out by the intestinal canal, and 
all gaseous matter by the lungs. 

We should not permit ourselves to be withheld 
by the idea of a vital principle, from considering in 
a chemical point of view the process of the transfor- 
mation of the food, and its assimilation by the 
various organs. This is the more necessary, as the 
views, hitherto held, have produced no results, and 
are quite incapable of useful application. 

Is it truly vitality, which generates sugar in the 
germ for the nutrition of young plants, or which 
gives to the stomach the power to dissolve, and to 
prepare for assimilation, all the matter introduced 
into it ? A decoction of malt possesses as little 
power to reproduce itself, as the stomach of a dead 
calf; both are, unquestionably, destitute of life. 

*' The examination of the air expired by consumptive persons, as 
well as of their blood, would doubtless throw much light on the nature 
o{ phthisis pulmonalis. Considered in a chemical point of view, the 
decomposition of the blood, as it takes place in the lungs, is a true 
process of putrefaction. (See Part II.) The lungs are also the seat 
of the transformation of the various substances contained in the blood. 
It certainly well merits consideration, that the most approved reme- 
dies for counteracting or stopping the progress of this frightful malady 
are precisely those which are found most efficacious in retarding putre- 
faction. Thus, it is well known, that much relief is afforded by a 
residence in works in which empyreumatic oils are manufactured by 
dry distillation, such as manufactories for the preparation of gas or sal- 
ammoniac. For the same reason, the respiration of wood vinegar 
(pyroligneous acid), of chlorine, and certain of the acids, has been 
recognised as a means of alleviating the disease. — L. 



74 ON THE ORIGIN AND ACTION OF HUMUS. 

But when amylin or starch is introduced into a de- 
coction of malt, it changes, first into a gummy-like 
matter, and lastly into sugar. Hard-boiled albumen 
and muscular fibre can be dissolved in a decoction 
of a calf's stomach, to which a few drops of muria- 
tic acid have been added, precisely as in the stom- 
ach itself.* (Schwann, Schulz.) 

The power, therefore, to effect transformations, 
does not belong to the vital principle : each trans- 
formation is owing to a disturbance in the attraction 
of the elements of a compound, and is consequently 
a purely chemical process. There is no doubt that 
this process takes place in another form from that 
of the ordinary decomposition of salts, oxides, or 
sulphurets. But is it the fault of chemistry that 
physiology has hitherto taken no notice of this new 
form of chemical action ? 

Physicians are accustomed to administer whole 
ounces of borax to patients suffering under urinary 
calculi, when it is known that the bases of all al- 
kaline salts formed by organic acids are carried 
through the urinary passages in the form of alkaline 
carbonates, capable of dissolving calculi (Wohler). 
Is this rational? The medical reports state, that 
upon the Rhine, where so much cream of tartar is 
consumed in wine, the only cases of calculous dis- 
orders are those which are imported from other dis- 
tricts. We know that the uric acid calculus is 
transformed into the mulberry calculus (which con- 
tains oxalic acid), when patients suffering under the 
former exchange the town for the country, where 
less animal and more vegetable food is used. Are 
all these circumstances incapable of explanation? 

The volatile oil of the roots of valerian may be 
obtained from the oil generated during the fermen- 
tation of potatoes (Dumas), and the oil of the 
SpircBa uhnaria from the crystalline matter of the 

* This remarkable action has been completely confirmed in this 
laboratory (Giessen), by Dr. Vogel, a highly distinguished young 
physiologist. — L. 



NATURE OF ORGANIC CHEMICAL PROCESSES. 75 

bai'k of the willow (Piria). We are able to form 
in our laboratories formic acid, oxalic acid, urea, 
and the crystalline substances existing in the liquid 
of the allantois of the cow, all products, it is said, 
of the vital principle. We see, therefore, that this 
mysterious principle has many relations in common 
with chemical forces, and that the latter can indeed 
replace it. What these relations are, it remains for 
physiologists to investigate. Truly it would be ex- 
traordinary if this vital principle, which uses every- 
thing for its own purposes, had allotted no share 
to chemical forces, which stand so freely at its dis- 
posal. We shall obtain that which is obtainable 
in a rational inquiry into nature, if we separate 
the actions belonging to chemical powers from those 
which are subordinate to other influences. But the 
expression " vital principle " must in the mean time 
be considered as of equal value with the terms 
specific or dynamic inmedicine: everything is specific 
which we cannot explain, and dynamic is the ex- 
planation of all which we do not understand; the 
terms having been invented merely for the purpose 
of concealing ignorance by the application of learned 
epithets. 

Transformations of existing compounds are con- 
stantly taking place during the whole life of a 
plant, in consequence of which, and as the results 
of these transformations, there are produced gaseous 
matters which are excreted by the leaves and blos- 
soms, solid excrements deposited in the bark, and 
fluid soluble substances which are eliminated by the 
roots. Such secretions are most abundant imme- 
diately before the formation and during the con- 
tinuance of the blossoms; they diminish after the 
development of the fruit. Substances containing a 
large proportion of carbon are excreted by the roots 
and absorbed by the soil. Through the expulsion 
of these matters unfitted for nutrition, the soil re- 
ceives again with usury the carbon which it had at 



76 ON THE ORIGIN AND ACTION OF HUJIUS. 

first yielded to the young plants as food, in the 
form of carbonic acid. 

The soluble matter thus acquired by the soil is 
still capable of decay and putrefaction, and by 
undergoing these processes furnishes renewed sour- 
ces of nutrition to another generation of plants; it 
becomes hiumis. The cultivated soil is thus placed 
in a situation exactly analogous to that of forests 
and meadows ; for the leaves of trees which fall in 
the forest in autumn, and the old roots of grass in 
the meadow, are likewise converted into humus by 
the same influence : a soil receives more carbon in 
this form than its decaying humus had lost as car- 
bonic acid. 

Plants do not exhaust the cai'bon of a soil in the 
normal condition of their growth; on the contrary, 
they add to its quantity. But if it is true that plants 
give back more carbon to a soil than they take from 
it, it is evident that their growth must depend upon 
the reception of nourishment from the atmosphere in 
the form of carbonic acid. The influence of humus 
upon vegetation is explained by the foregoing facts 
in the most clear and satisfactory manner. 

Humus does not nourish plants by being taken up 
and assimilated in its unaltered state, but by pre- 
senting a slow and lasting source of carbonic acid, 
which is absorbed by the roots, and is the principal 
nutriment of young plants at a time when, being des- 
titute of leaves, they are unable to extract food from 
the atmosphere. 

In former periods of the earth's history, its sur- 
face was covered with plants, the remains of which 
are still found in the coal formations. These plants, 
— the gigantic monocotyledons, ferns, palms, and 
reeds, — belong to a class to which nature has given 
the power, by means of an immense extension of their 
leaves, to dispense with nourishment from the soil. 
They resemble in this respect the plants which we 
raise from bulbs and tubers, and which live while 
young upon the substances contained in their seed, 



ITS USE EXPLAINED. 77 

and require no food from the soil when their exterior 
organs of nutrition are formed. This class of plants 
is even at present ranked amongst those which do 
not exhaust the soil. 

The necessity of the existence of plants such as 
these at the commencement of vegetation, must now 
be apparent. Humus is a product of the decay of 
vegetable matter, and therefore could not have ex- 
isted to supply the first plants with the food neces- 
sary for the development of the more delicate kinds. 
Hence the plants capable of flourishing under such 
circumstances could only be those which receive their 
nourishment from the air alone. By their decay, 
however, the soil in which they grew became sup- 
plied with vegetable matter, and the progress of 
vegetation must have furnished to the earth materi- 
als adapted for the development of those plants, 
which depend upon the nutriment contained in the 
soil, until those organs are formed which are des- 
tined for the assumption of nourishment from the 
atmosphere. 

The plants of every former period are distinguished 
from those of the present by the inconsiderable de- 
velopment, of their roots. Fruit, leaves, seeds, near- 
ly every part of the plants of a former world, except 
the roots, are found in the brown coal formation. 
The vascular bundles, and the perishable cellular tis- 
sue, of which their roots consisted, have been the 
first to suffer decomposition. But when we examine 
oaks and other trees, which in consequence of revo- 
lutions of the same kind occurring in later ages have 
undergone the same changes, we never find their 
roots absent. 

The verdant plants of warm climates are very often 
such as obtain from the soil only a point of attach- 
ment, and are not dependent on it for their growth. 
How extremely small are the roots of the Cactus, 
Sedtim, and Sempervivum, in proportion to their 
mass, and to the surface of their leaves ! Large for- 
ests are often found growing in soils absolutely des- 



78 ON THE ORIGIN AND ACTION OF HUMUS. 

titute of carbonaceous matter ; and the extensive 
prairies of the Western Continent show that the car- 
bon necessary for the sustenance of a plant may be 
entirely extracted from the atmosphere. Again, in 
the most dry and barren sand, where it is impossible 
for nourishment to be obtained through the roots, we 
see the milky-juiced plants attain complete perfec- 
tion. The moisture necessary for the nutrition of 
these plants is derived from the atmosphere, and 
when assimilated is secured from evaporation by the 
nature of the juice itself. Caoutchouc and wax, 
w^hich are formed in these plants, surround the water, 
as in oily emulsions, with an impenetrable envelope 
by which the fluid is retained, in the same manner as 
milk is prevented from evaporating by the skin 
which forms upon it. These plants, therefore, be- 
come turgid with their juices. 

Particular examples might be cited of plants, which 
have been brought to maturity, upon a small scale, 
without the assistance of mould ; but fresh proofs 
of the accuracy of our theory respecting the origin 
of carbon would be superfluous and useless, and 
could not render more striking, or more convincing, 
the arguments already adduced. It must not, how- 
ever, be left unmentioned, that common wood char- 
coal, by virtue merely of its ordinary well-know^n 
properties, can completely replace vegetable mould 
or hmnus. The experiments of Lukas, which are 
appended to this work, spare me all further remarks 
upon its efficacy. 

Plants thrive in powdered charcoal, and may be 
brought to blossom and bear fruit if exposed to the 
influence of the rain and the atmosphere ; the char- 
coal may be previously heated to redness. Charcoal 
is the most " indiff'erent " and most unchangeable 
substance known ; it may be kept for centuries with- 
out change, and is therefore not subject to decompo- 
sition. The only substances which it can yield to 
plants are some salts, which it contains, amongst 
•which is silicate of potash. It is known, however, 



NOT INDISPENSABLE FOR PLANTS. 79 

to possess the power of condensing gases within its 
pores, and particularly carbonic acid. And it is by 
virtue of this power that the roots of plants are sup- 
plied in charcoal, exactly as in humus, with an at- 
mosphere of carbonic acid and air, which is renewed 
as quickly as it is abstracted. 

In charcoal powder, which had been used for this 
purpose by Lukas for several years, Buchner found a 
brown substance soluble in alkalies. This substance 
was evidently due to the secretions from the roots 
of the plants which grew in it. 

A plant placed in a closed vessel in which the air, 
and therefore the carbonic acid, cannot be renewed, 
dies exactly as it would do in the vacuum of an air- 
pump, or in an atmosphere of nitrogen or carbonic 
acid, even though its roots be fixed in the richest 
mould.* 

Plants do not, however, attain maturity, under or- 
dinary circumstances, in charcoal powder, when they 
are moistened with pure distilled water instead of 
rain or river water. Rain water must, therefore, con- 
tain within it one of the essentials of vegetable life; 
and it will be shown, that this is the presence of a 
compound containing nitrogen, the exclusion of which 
entirely deprives humus and charcoal of their influ- 
ence upon vegetation. 

* A few years since I had an opportunity of observing a striking in- 
stance of tlie effect of carbonic acid upon vegetation in the volcanic 
island of St. Michael (Azores). The gas issued from a fissure in the 
base of a hill of trachyte and tuffa from which a level field of some 
acres extended. This field, at the time of my visit, was in part covered 
with Indian corn. The corn at the distance often or fifteen yards from 
the fissure, was nearly full grown, and of the usual height, but the 
height regularly diminished until within five or sis feet of the hill, 
where it attained but a few inches. This effect was owing to the great 
specific gravity of the carbonic acid, and its spreading upon the ground, 
but as the distance increased, and it became more and mere mingled 
with atmospheric air, it had produced less and less effect. — IV. 



80 ON THE ASSIMILATION OF HYDROGEN 



CHAPTER IV. 

ON THE ASSIMILATION OF HYDROGEN. 

The atmosphere contains the principal food of 
plants in the form of carbonic acid, in the state, 
therefore, of an oxide. The solid part of plants 
(woody fibre) contains carbon and the constituents 
of water, or the elements of carbonic acid, together 
with a certain quantity of hydrogen. It has former- 
ly been mentioned that water consists of the two 
gases, oxygen and hydrogen. The range of affinity 
possessed by both these elements is so extensive, that 
numerous causes occur which effect the decomposi- 
tion of water. Indeed, there is no compound which 
plays a more general or more important part in the 
phenomena of combination and decomposition. We 
can conceive the wood to arise from a combination 
of the carbon of the carbonic acid with the elements 
of water, under the influence of solar light. In this 
case, 72-35 parts of oxygen, by weight, must be sep- 
arated as a gas for every 27-65 parts of carbon, 
which are assimilated by a plant ; for this is the 
composition of carbonic acid in 100 parts. Or, what 
is much more probable, plants, under the same cir- 
cumstances, may decompose water, the hydrogen of 
which is assimilated along with carbonic acid, whilst 
its oxygen is separated. If the latter change takes 
place, 8-04 parts of hydrogen must unite with 100 
parts of carbonic acid, in order to form w^oody fibre, 
and the 72-35 parts by weight of oxygen, which was 
in combination with the hydrogen of the water, and 
which exactly corresponds in quantity with the oxy- 
gen contained in the carbonic acid, must be separ- 
ated in a gaseous form. 

Each acre of land, which produces 10 cwts. of 
carbon, gives annually to the atmosphere 2865 lbs. of 
free oxygen gas. The specific weight of oxygen is 



BY THE DECOMPOSITION OF WATER. Ol 

expressed by the number 1-1026; hence 1 cubic me- 
tre of oxygen weighs 3*157 lbs., and 2865 lbs. of 
oxygen correspond to 908 cubic metres, or 32,007 
cubic feet. 

An acre of meadow, wood, or cultivated land in 
general replaces, therefore, in the atmosphere as 
much oxygen as is exhausted by 10 cwts. of carbon, 
either in its ordinary combustion in the air or in the 
respiratory process of animals. 

It has been mentioned at a former page that pure 
woody fibre contains carbon and the component parts 
of water, but that ordinary wood contains more hy- 
drogen than corresponds to this proportion. This 
excess is owing to the presence of the green princi- 
ple of the leaf, wax, resin, and other bodies rich in 
hydrogen. Water must be decomposed, in order to 
furnish the excess of this element, and consequently 
one equivalent of oxygen must be given back to the 
atmosphere for every equivalent of hydrogen appro- 
priated by a plant to the production of those sub- 
stances. The quantity of oxygen thus set at liberty 
cannot be insignificant, for the atmosphere must re- 
ceive 547 cubic feet of oxygen for every pound of 
hydrogen assimilated. 

It has already been stated, that a plant, in the 
formation of woody fibre, must always yield to the 
atmosphere the same proportional quantity of oxy- 
gen ; that the volume of this gas set free would be 
the same whether it were due to the decomposition 
of carbonic acid or of w^ater. A little consideration 
will show that this must be the case. It has repeat- 
edly been stated, that woody fibre contains carbon 
in combination with oxygen and hydrogen in the 
same proportion in which they exist in water. Water 
contains 1 equivalent of each element, whilst carbon- 
ic acid consists of 1 equivalent of carbon, united to 
2 equivalents of oxygen. In the formation of woody 
fibre, 2 equivalents of oxygen must therefore be lib- 
erated. The woody fibre can only be formed in one 
of two ways : either the carbon of carbonic acid 



82 ASSIMILATION OF HYDROGEN 

unites directly with water, or the hydrogen of water 
combines with the oxygen of the carbonic acid. In 
the former of these cases, the two equivalents of ox- 
ygen in the carbonic acid must be liberated; in the 
latter, two atoms of water must be decomposed, the 
hydrogen of which unites with the oxygen of the 
carbonic acid, whilst the oxygen of the water, thus 
set free, is disengaged in the state of a gas. It 
was considered most probable that the latter was 
the case. 

From their generating caoutchouc, wax, fats, and 
volatile oils containing hydrogen in large quantity, 
and no oxygen, we may be certain that plants pos- 
sess the property of decomposing water, because 
from no other body could they obtain the hydrogen 
of those matters. It has also been proved by the 
observations of Humboldt on the fungi, that water 
may be decomposed without the assimilation of hy- 
drogen. Water is a remarkable combination of 
two elements, which have the power to separate 
themselves from one another, in innumerable pro- 
cesses, in a manner imperceptible to our senses ; while 
carbonic acid, on the contrary, is only decomposable 
by violent chemical action. 

Most vegetable structures contain hydrogen in 
the form of water, which can be separated as such, 
and replaced by other bodies ; but the hydrogen 
which is essential to their constitution cannot pos- 
sibly exist in the state of water. 

All the hydrogen necessary for the formation of 
an organic compound is supplied to a plant by the 
decomposition of water. The process of assimila- 
tion, in its most simple form, consists in the extrac- 
tion of hydrogen from water, and carbon from car- 
bonic acid, in consequence of which, either all the 
oxygen of the water and carbonic acid is separated, 
as in the formation of caoutchouc, the volatile oils 
which contain no oxygen, and other similar sub- 
stances, or only a part of it is exhaled. 

The known composition of the organic compounds 



BY THE DECOMPOSITION OF WATER. 83 

most generally present in vegetables, enables us to 
state in definite proportions the quantity of oxygen 
separated during their formation. 

36 eq. carbonic acid and 22 eq. hydrogen derived ) ,j^ , „., 

from 22 eq. water . . . . ) "^"2/ ■'' *'"'C' 

with the separation of 72 eq. oxygen. 

36 eq. carbonic acid and 36 eq. hydrogen derived 7 „ 

from 36 eq. water .... 5 ~ ^^S^^t 

with the separation of 72 eq. oxygen. 

36 eq. carbonic acid and 30 eq. hydrogen derived ; „ , 

from 30 eq. water . . . . 5 " '=>^«''''«. 

with the separation of 72 eq oxygen. 

36 eq. carbonic acid and 16 eq. hydrogen derived ) „, . - . , 

from 16 eq. water .... ^— tannic Mad, 

with the separation of 64 eq. oxygen. 

36 eq. carbonic acid and 18 eq. hydrogen derived ) ™ ■ a -j 

ti-om 18 eq. water .... ^ — lartanc Jlcia, 

with the separation of 4.5 eq. oxygen. 

36 eq. carbonic acid and 18 eq. liydrogen derived \ ,, ,. a -j 

from 18 eq. water .... ^ — MaucJicia, 

with the separation of 54 eq. oxygen. 

36 eq. carbonic acid and 24 eq. hydrogen derived ) ni fT 

from 24 eq. water .... ^ — uuojiurpentme, 

with the separation of 84 eq. oxygen. 

It will readily be perceived, that the formation 
of the acids is accompanied with the smallest 
separation of oxygen; that the amount of oxygen 
set free increases with the production of the so- 
named neutral substances, and reaches its maximum 
in the formation of the oils. Fruits remain acid in 
cold summers; while the most numerous trees under 
the tropics are those which produce oils, caoutchouc, 
and other substances containing very little oxygen. 
The action of sunshine and influence of heat upon 
the ripening of fruit is thus, in a certain measure, 
represented by the numbers above cited. 

The green resinous principle of the leaf diminishes 
in quantity, while oxygen is absorbed, when fruits 
are ripened in the dark ; red and yellow coloring 
matters are formed ; tartaric, citric, and tannic acids 
disappear, and are replaced by sugar, ainylin, or 
gum. 6 eq. Tartaric Acid, by absorbing 6 eq. oxy- 
gen from the air, form Grape Sugar, with the separa- 
tion of 12 eq. carbonic acid. 1 eq. Tannic Acid, 
by absorbing 8 eq. oxygen from the air, and 4 eq. 



84 ASSIMILATIO OF HYDROGEN. 

water, form 1 eq. of Amylin, or starch, with separa- 
tion of 6 eq. carbonic acid. 

We can explain, in a similar manner, the forma- 
tion of all the component substances of plants 
which contain no nitrogen, whether they are pro- 
duced from carbonic acid and water, with separation 
of oxygen, or by the conversion of one substance 
into the other, by the assimilation of oxygen and 
separation of carbonic acid. We do not know in 
what form the production of these constituents takes 
place; in this respect, the representation of their 
formation which we have given must not be received 
in an absolute sense, it being intended only to ren- 
der the nature of the process more capable of ap- 
prehension; but it must not be forgotten, that if the 
conversion of tartaric acid into sugar, in grapes, be 
considered as a fact, it must take place under all 
circumstances in the same proportions. 

The vital process in plants is, with reference to 
the point we have been considering, the very re- 
verse of the chemical processes engaged in the for- 
mation of salts. Carbonic acid, zinc, and water, 
when brought into contact, act upon one another, 
and hydrogen is separated, while a white pulverulent 
compound is formed, which contains carbonic acid, 
zinc, and the oxygen of the water. A living plant 
represents the zinc in this process : but the process 
of assimilation gives rise to compounds, which con- 
tain the elements of carbonic acid and the hydrogen 
of water, whilst oxygen is separated. 

Decay has been described above as the great 
operation of nature, by which that oxygen, which 
was assimilated by plants during life, is again re- 
turned to the atmosphere. During the progress of 
growth, plants appropriate carbon in the form of 
carbonic acid, and hydrogen from the decomposition 
of water, the oxygen of which is set free, together 
with a part of all of that contained in the carbonic 
acid. In the process of putrefaction, a quantity of 
water, exactly corresponding to that of the hydro- 



SOURCE AND ASSIMILATION OF NITROGEN. 85 

gen, is again formed by extraction of oxygen from 
the air ; while all the oxygen of the organic matter 
is returned to the atmosphere in the form of carbonic 
acid. Vegetable matters can emit carbonic acid, 
during their decay, only in proportion to the quan- 
tity of oxygen which they contain ; acids, therefore, 
yield more carbonic acid than neutral compounds ; 
while fatty acids, resin, and wax, do not putrefy ; 
they remain in the soil without any apparent change. 
The numerous springs which emit carbonic acid 
in the neighborhood of extinct volcanoes, must be 
regarded as another means of compensating for the 
carbonic acid absorbed and retained by plants dur- 
ing life, and consequently as a source by which 
oxygen is supplied to the atmosphere. Bischof 
calculated that the springs of carbonic acid in the 
Eifel (a volcanic district near Coblenz) send into 
the air every day more than 99,000 lbs. of carbonic 
acid, corresponding to 71,000 lbs. of pure oxygen. 



CHAPTER V. 

ON THE ORIGIN AND ASSIMILATION OF NITROGEN. 

We cannot suppose that a plant could attain 
maturity, even in the richest vegetable mould, with- 
out the presence of matter containing nitrogen; 
since we know that nitrogen exists in every part of 
the vegetable structure. The first and most impor- 
tant question to be solved, therefore, is : How and 
in what form does nature furnish nitrogen to vege- 
table albumen, and gluten, to fruits and seeds 1 

This question is susceptible of a very simple solu- 
tion. 

Plants, as we know, grow perfectly well in pure 
charcoal, if supplied at the same time with rain- 
water. Rain-water can contain nitrogen only in 
two forms, either as dissolved atmospheric air, or as 



86 SOURCE AND ASSIIMILATION OF NITROGEN. 

ammonia, which consists of this element and hydro- 
gen. Now, the nitrogen of the air cannot be made 
to enter into combination with any element except 
oxygen, even by the employment of the most power- 
ful chemical means. We have not the slightest 
reason for believing that the nitrogen of the atmo- 
sphere takes part in the processes of assimilation of 
plants and animals ; on the contrary, we know that 
many plants emit the nitrogen which is absorbed by 
their roots, either in the gaseous form, or in solution 
in water. But there are on the other hand numerous 
facts, showing, that the formation in plants of sub- 
stances containing nitrogen, such as gluten, takes 
place in proportion to the quantity of this element 
which is conveyed to their roots in the state of 
ammonia,* derived from the putrefaction of animal 
matter. 

Ammonia, too, is capable of undergoing such a 
multitude of transformations, when in contact with 
other bodies, that in this respect it is not inferior to 
water, which possesses the same property in an 
eminent degree. It possesses properties which we 
do not find in any other compound of nitrogen : 
when pure, it is extremely soluble in water; it forms 
soluble compounds with all the acids ; and when in 
contact with certain other substances, it completely 
resigns its character as an alkali, and is capable of 
assuming the most various and opposite forms. 
Formate of ammonia f changes, under the influence 
of a high temperature, into hydrocyanic acid and 
water, without the separation of any of its elements. 

* Ammonia is a compound gas, consisting of one volume of nitrogen 
and three volumes of hydrogen. It is produced during the decompo- 
sition of many animal substances. It is given off" when sal-ammoniac 
and lime are rubbed together. It was formerly called volatile alkali. 

t Formic acid (p 70. n ) is also obtained from sugar and many other 
vegetable substances ; a pound of sugar yields a quantity capable of 
saturating five or six ounces of carbonate of lime. A process for 
obtaining it has been given by Emmet in the Jlmcriam Journal, Vol. 
XXXII. p. 140. See details in Webster's Manual of Chemistry, 2d 
edition, p. 374. 

Its composition is carbon 2, water 3. With ammonia and other 
bases it yields the salts called formates. 



SOURCE AND ASSIJIILATION OF NITROGEN. 87 

Ammonia forms urea,* with cyanic acid,t and a 
series of crystalline compounds, with the volatile 
oils of mustard and bitter almonds. It changes 
into splendid blue or red coloring matters, when in 
contact with the bitter constituent of the bark of 
the apple-tree (^phloridzi7i), with the sweet principle 
of the Variolaria dealbata (orciii), or with the taste- 
less matter of the Rocella tifictoria (^erythrin). All 
blue coloring matters which are reddened by acids, 
and all red coloring substances which are rendered 
blue by alkalies, contain nitrogen, but not in the 
form of a base. 

These facts are not sufficient to establish the 
opinion that it is ammonia which affords all vegeta- 
bles, without exception, the nitrogen which enters 
into the composition of their constituent substances. 
Considerations of another kind, however, give to 
this opinion a degree of certainty which completely 
excludes all other views of the matter. 

Let us picture to ourselves the condition of a 
well-cultured farm, so large as to be independent of 
assistance from other quarters. On this extent of 
land there is a certain quantity of nitrogen contained 
both in corn and fruit which it produces, and in the 
men and animals which feed upon them, and also in 
their excrements. We shall suppose this quantity 
to be known. The land is cultivated without the 
importation of any foreign substance containing 
nitrogen. Now, the products of this farm must be 
exchanged every year for money, and other necessa- 
ries of life — for bodies, therefore, which contain no 
nitrogen. A certain proportion of nitrogen is ex- 
ported with corn and cattle; and this exportation 
takes place every year, without the smallest com- 
pensation; yet after a given number of years, the 
quantity of nitrogen will be found to have increased. 

* Urea was discovered in urine, being a constituent of uric acid. It 
contains the elements of cyanate of ammonia (NH4 O -f- C4 NO). 

t This acid consists of 1 cyanogen and 1 oxygen. See Webster's 
Chemistry, p. 398. 



88 SOURCE AND ASSIMILATION OF NITROGEN. 

Whence, we may ask, comes this increase of nitro- 
gen ? The nitrogen in the excrements cannot repro- 
duce itself, and the earth cannot yield it. Plants, 
and consequently animals, must, therefore, derive 
their nitrogen from the atmosphere. 

It will in a subsequent part of this work be shown, 
that the last products of the decay and putrefaction 
of animal bodies present themselves in two different 
forms. They are in the form of a combination of 
hydrogen and nitrogen, — a7nnionia, — in the tem- 
perate and cold climates, and in that of a compound 
containing oxygen, — nitric acid, — in the tropics 
and hot climates. The formation of the latter is pre- 
ceded by the production of the first. Ammonia is 
the last product of the putrefaction of animal bodies ; 
nitric acid is the product of the transformation of 
ammonia. A generation of a thousand million men 
is renewed every thirty years : thousands of millions 
of animals cease to live, and are reproduced, in a 
much shorter period. Where is the nitrogen which 
they contained during life ? There is no question 
which can be answered with more positive certainty. 
All animal bodies during their decay yield the nitro- 
gen which they contain to the atmosphere, in the 
form of ammonia. Even in the bodies buried sixty 
feet under ground in the churchyard of the Eglise 
des Innocens, at Paris, all the nitrogen contained in 
the adipocire was in the state of ammonia.* Ammo- 
nia is the simplest of all compounds of nitrogen; 
and hydrogen is the element for which nitrogen pos- 
sesses the most powerful affinity. 

The nitrogen of putrefied animals is contained in 
the atmosphere as ammonia, in the form of a gas 

* In 1786 - 7, when this churchyard was cleared out, it was discov- 
ered that many of the bodies had been converted into a soapy white 
substance. Fourcroy attempted to prove that tJie fatty body was an 
ammoniacal soap, containing phosphate of lime, that the fat was simi- 
lar to spermaceti and to wax, hence he called it adipocire. Its naelting 
point was 120..")° F. 

For notice of the analysis and opinions of other chemists, see Uke's 
Dictionary of Arts and Manufactures, p. 14. 



PRODUCTS OF PUTREFACTION. 89 

which is capable of entering into combination with 
carbonic acid and of forming a volatile salt. Am- 
monia in its gaseous form, as well as all its volatile 
compounds, is of extreme solubility in water.* Am- 
monia, therefore, cannot remain long in the atmo- 
sphere, as every shower of rain must condense it, and 
convey it to the surface of the earth. Hence also, 
rain-water must at all times contain ammonia, though 
not always in equal quantity. It must be greater in 
summer than in spring or in winter, because the in- 
tervals of time between the showers are in summer 
greater ; and when several wet days occur, the rain 
of the first must contain more of it than that of the 
second. The rain of a thunder-storm, after a long- 
protracted drought, ought for this reason to contain 
the greatest quantity which is conveyed to the earth 
at one time. 

But we have formerly stated, that all the analyses 
of atmospheric air hitherto made have failed to de- 
monstrate the presence of ammonia, although, ac- 
cording to our view, it can never be absent. Is it 
possible that it could have escaped our most delicate 
and most exact apparatus ? The quantity of nitro- 
gen contained in a cubic foot of air is certainly ex- 
tremely small, but, notwithstanding this, the sum of 
the quantities of nitrogen from thousands and mil- 
lions of dead animals is more than sufficient to sup- 
ply all those living at one time with this element. 

From the tension of aqueous vapor at 15° C. (59° 
F.) = 6,98 lines (Paris measure), and from its known 
specific gravity at 0° C. (32° F.), it follows that 
when the temperature of the air is 59° F. and the 
height of the barometer 28", 1 cubic metre or 35*3 
cubic feet of aqueous vapor are contained in 487 
cubic metres, or 17,198 cubic feet of air; 35*3 cubic 
feet of aqueous vapor weigh about 1.65 lb. Conse- 
quently, if we suppose that the air saturated with 
moisture at 59° F. allows all the water which it con^ 

* According to Dr. Thomson, water absorbs 780 times its bulk of 
ammonia. 



90 SOURCE AND ASSIMILATION OF NITROGEN. 

tains in the gaseous form to fall as rain, then l-l 
pound of rain water must be obtained from every 
11,477 cubic feet of air. The whole quantity of am- 
monia contained in the same number of cubic feet 
will also be returned to the earth in this one pound 
of rain-water. But if the 11,477 cubic feet of air 
contain a single grain of ammonia, then ten cubic 
inches, — the quantity usually employed in an analy- 
sis, — must contain only 0.000000050 of a grain. 
This extremely small proportion is absolutely inap- 
preciable by the most delicate and best eudiometer ; * 
it might be classed among the errors of observation, 
even were its quantity ten thousand times greater. 
But the detection of ammonia must be much more 
easy when a pound of rain-water is examined, for 
this contains all the gas that was diffused through 
11,477 cubic feet of air." 

If a pound of rain-water contain only ,^th of a grain 
of ammonia, then a field of 26,910 square feet must 
receive annually upwards of 88 lbs. of ammonia, or 
71 lbs. of nitrogen ; for by the observations of Schu- 
bler, which were formerly alluded to, about 770,000 
lbs. of rain fall over this surface in four months, and 
consequently the annual fall must be 2,310,000 lbs. 
This is much more nitrogen than is contained in the 
form of vegetable albumen and gluten, in 2920 lbs. 
of wood, 3085 lbs. of hay, or 200 cwt. of beet-root, 
which are the yearly produce of such a field ; but it 
is less than the straw, roots, and grain of corn, which 
might grow on the same surface, would contain. f 

* A eudiometer is an instrument used in the analyses of the atmo- 
sphere. It means a measure of purity. It is also used in the analysis 
of mixtures of gases. Several varieties are described in Webster's 
Mannal, p. 137. 

t The advocates of the importance of humus as a nourishment for 
plants, being driven from their position by the facts brought forward in 
the preceding chapters, have found in the ammonia of the atmosphere 
an explanation of the manner in which humus acquires its solubility, 
and therefore its capability of being assimilated by plants. Now, it is 
very true that humic acid is soluble in ammonia ; but the humic acid 
of chemists is nnt contained in soils. Were it so, on treating mould with 
water we should obtain a dark-colored solution of humate of ammonia. 
But we obtain a solution whicii is entirely devoid of this acid. It can- 



EXISTENCE OF AMBIONIA IN RAIN. 91 

Experiments made in this laboratory (Giessen) 
with the greatest care and exactness have placed the 
presence of ammonia in rain-water beyond all doubt. 
It has hitherto escaped observation, because no per- 
son thouofht of searchinjj for it.* All the rain-water 
employed in this inquiry was collected 600 paces 
southwest of Giessen, whilst the wind was blowing 
in the direction of the town. When several hundred 
pounds of it were distilled in a copper still, and the 
first two or three pounds evaporated with the addi- 
tion of a little muriatic acid, a very distinct crystal- 
lization of sal-ammoniac was obtained : the crystals 
had always a brown or yellow color. 

Ammonia may likewise be always detected in snow- 
water. Crystals of sal-ammoniac were obtained by 
evaporating in a vessel with muriatic acid several 
pounds of snow, which were gathered from the sur- 
face of the ground in March, when the snow had a 
depth of 10 inches. Ammonia was set free from 
these crystals by the addition of hydrate of lime. 
The inferior layers of snow which rested upon the 
ground contained a quantity decidedly greater than 
those which formed the surface. f 

It is worthy of observation, that the ammonia con- 
tained in rain and snow water possesses an offensive 
smell of perspiration and animal excrements, — a 
fact which leaves no doubt respecting its origin. 

not be too distinctly kept in mind that humic acid is the product of the 
decomposition of //7<mMS, by means of caustic alkalies. Again, if the 
colored solutions of humates of ammonia, lime, or magnesia, be poured 
upon good mould or decayed oak wood (which is nearly pure hrimus), 
and allowed to filter, the solutions are observed to pass through quite 
colorless ; they are decolorized just as if they had been filtered through 
charcoal. Here, then, humus possesses the property of extracting hu- 
mrc acid from water ; or, in other words, soils have the power of ren- 
dering humic acid insoluble, or unfit for assimilation. — Ed. 

* It has been discovered by Mr. Hayes in rain-water in Vermont, 
— and in hailstones by M Girardin, see London and Edinburgh Philo- 
sophical Magazine, 1839, Vol. XV. p. 252. See note in Appendix. 

t Johnston detected it in snow which fell at Durham, G. B., by add- 
ing two drops of sulphuric acid to four pints of snow-water, evaporating 
to dryness, and mixing the dr};^ mass with quicklime or caustic potash 
The residual mass contained a brown organic matter, mixed with the 
sulphaie of ammonia. 



92 SOURCE AND ASSIMILATION OF NITROGEN. 

Hiinefield has proved that all the springs in Greifs- 
walde, Wick, Eldena, and Kostenhagen, contain car- 
bonate and nitrate of ammonia. Ammoniacal salts 
have been discovered in many mineral springs in 
Kissingen and other places. The ammonia of these 
salts can only arise from the atmosphere. 

Any one may satisfy himself of the presence of 
ammonia in rain by simply adding a little sulphuric 
or muriatic acid to a quantity of rain-water, and 
evaporating this nearly to dryness in a clean porce- 
lain basin. The ammonia remains in the residue, in 
combination with the acid employed ; and may be 
detected either by the addition of a little chloride 
of platinum, or more simply by a little powdered 
lime, which separates the ammonia, and thus renders 
its peculiar pungent smell sensible.* The sensation 
which is perceived upon moistening the hand with 
rain-water, so different from that produced by pure 
distilled water, and to which the term softness is 
vulgarly applied, is also due to the carbonate of 
ammonia contained in the former.f 

The ammonia which is removed from the atmo- 
sphere by rain and other causes, is as constantly re- 
placed by the putrefaction of animal and vegetable 
matters. A certain portion of that which falls with 
the rain evaporates again with the water, but another 
portion is, we suppose, taken up by the roots of 
plants, and, entering into new combinations in the 
different organs of assimilation, produces albumen, 
gluten, quinine, morphia, cyanogen, and a number 
of other compounds containing nitrogen. The chem- 
ical characters of ammonia render it capable of 

* Since tlie appearance of the first edition, this experiment has been 
repeated by many in France, Germany, America, and England, and the 
existence of ammonia in the atmosphere lias been completely confirm- 
ed. The ass'^rlion, that tliis ammonia possesses the "offensive smell 
of perspiration and animal excrements," has been ridiculed by many 
as fanciful, — by none, however, who have made the experiment. The 
experiment is so exceedingly easy to perform, that any one may con- 
vince himself of tlie accuracy of the statement. — En. 

t A small quantity of iimmonia writer, added to what is commonly 
called hard water, will give it the softness of rain or snow water. 



EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 93 

entering into such combinations, and of undergoing 
numerous transformations. We have now only to 
consider whether it really is taken up in the form 
of ammonia by the roots of plants, and in that form 
applied by their organs to the production of the 
azotized matters contained in them. This question 
is susceptible of easy solution by well-known facts. 

In the year 1834, I was engaged with Dr. Wil- 
brand, Professor of Botany in the University of 
Giessen, in an investigation respecting the quantity 
of sugar contained in different varieties of maple- 
trees, which grew upon soils which were not ma- 
nured. We obtained crystallized sugars from all, 
by simply evaporating their juices, without the ad- 
dition of any foreign substance ; and we unexpected- 
ly made the observation, that a great quantity of 
ammonia was emitted from this juice when mixed 
with lime, and also from the sugar itself during its 
refinement. The vessels which hung upon the trees 
in order to collect the juice were watched with 
greater attention, on account of the suspicion that 
some evil-disposed persons had introduced urine 
into them, but still a large quantity of ammonia was 
again found in the form of neutral salts. The juice 
had no color, and had no reaction on that of vegeta- 
bles. Similar observations were made upon the 
juice of the birch tree ; the specimens subjected to 
experiment were taken from a wood several miles 
distant from any house, and yet the clarified juice, 
evaporated with lime, emitted a strong odor of 
ammonia. 

In the manufactories of beet-root sugar, many 
thousand cubic feet of juice are daily purified with 
lime, in order to free it from vegetable albumen and 
gluten, and it is afterwards evaporated for crystalli- 
zation. Every person who has entered such a manu- 
factory must have been astonished at the great 
quantity of ammonia which is volatilized along with 
the steam. This ammonia must be contained in the 
form of an ammoniacal salt, because the neutral 



94 SOURCE AND ASSIMILATION OF NITROGEN. 

juice possesses the same characters as the solution 
of such a salt in water ; it acquires, namely, an 
acid reaction during evaporation, in consequence of 
the neutral salt being converted by loss of ammonia 
into an acid salt. The free acid which is thus 
formed is a source of loss to the manufacturers of 
sugar from beet-root, by changing a part of the 
sugar into uncrystallizable grape sugar and syrup. 

The products of the distillation of flowers, herbs, 
and roots, with water, and all extracts of plants 
made for medicinal purposes, contain ammonia. The 
unripe, transparent, and gelatinous pulp of the al- 
mond and peach emit much ammonia when treated 
with alkalies. (Robiquet.) The juice of the fresh 
tobacco leaf contains ammoniacal salts. The water 
which exudes from a cut vine, when evaporated 
with a few drops of muriatic acid, also yields a 
gummy, deliquescent mass, which evolves much am- 
monia on the addition of lime. Ammonia exists in 
every part of plants, in the roots (as in beet-root), 
in the stem (of the maple-tree), and in all blossoms 
and fruit in an unripe condition. 

The juices of the maple and birch contain both 
sugar and ammonia, and therefore afford all the con- 
ditions necessary for the formation of the azotized 
components of the branches, blossoms, and leaves, 
as well as of those which contain no azote or nitro- 
gen. In proportion as the development of those 
parts advances, the ammonia diminishes in quantity, 
and when they are fully formed, the tree yields no 
more juice. 

The employment of animal manure in the cultiva- 
tion of grain, and the vegetables which serve for 
fodder to cattle, is the most convincing proof that 
the nitrogen of vegetables is derived from ammonia. 
The quantity of gluten in wheat, rye, and barley, is 
very different; these kinds of grain also, even when 
ripe, contain this compound of nitrogen in very 
different proportions. Proust found French wheat 
to contain 12-5 per cent, of gluten; Vogel found that 



VARIABLE QUANTITIES OF GLUTEN IN WHEAT. 95 

the Bavarian contained 24 per cent. ; Davy obtained 
19 per cent, from winter, and 24 from summer 
wheat; from Sicilian 21, and from Barbary wheat 
19 per cent. The meal of Alsace wheat contains, 
according to Boussingault, 17-3 per cent, of gluten; 
that of wheat grown in the " Jardin des Plantes " 
26-7, and that of winter wheat 3"33 per cent. Such 
great differences must be owing to some cause, and 
this we find in the different methods of cultivation. 
An increase of animal manure gives rise not only 
to an increase in the number of seeds, but also to 
a most remarkable difference 'in the proportion of 
the substances containing nitrogen, such as the 
gluten which they contain. 

Animal manure, in as far as regards the assimila- 
tion of nitrogen, acts only by the formation of am- 
monia. One hundred parts of wheat grown on a 
soil manured with cow-dung (a manure containing 
the smallest quantity of nitrogen), afforded only 
11-95 parts of gluten, and 64*34 parts of amylin, or 
starch; whilst the same quantity, grown on a soil 
manured with human urine, yielded the maximum of 
gluten, namely 35-1 per cent. Putrefied urine con- 
tains nitrogen in the forms of carbonate, phosphate, 
and lactate of ammonia, and in no other form than 
that of ammoniacal salts. 

" Putrid urine is employed in Flanders as a ma- 
nure with the best results. During the putrefaction 
of urine, ammoniacal salts are formed in large quan- 
tity, it may be said exclusively; for under the in- 
fluence of heat and moisture, urea, the most promi- 
nent ingredient of the urine, is converted into car- 
bonate of ammonia. The barren soil on the coast 
of Peru is rendered fertile by means of a manure 
called Guano, which is collected from several islands 
in the South Sea.* It is sufficient to add a small 
quantity of guano to a soil, which consists only of 

* The guano, whicli forms a stratum several feet in thickness upon 
the surface of these islands, consists of the putrid excrements of in- 



96 SOURCE AND ASSIMILATION OF NITROGEN. 

sand and clay, in order to procure the richest crop 
of maize. The soil itself does not contain the 
smallest particle of organic matter, and the manure 
employed is formed only of urate, phosphate, oxa- 
late, and carbonate of ammonia, together with a few 
earthy salts.*" 

Ammonia, therefore, must have yielded the nitrogen 
to these plants. Gluten is obtained not only from 
corn, but also from grapes and other plants ; but 
that extracted from the grapes is called vegetable 
albumen, although it is identical in composition and 
properties with the ordinary gluten. 

It is ammonia which yields nitrogen to the vege- 
table albumen, the principal constituent of plants ; 
and it must be ammonia which forms the red and blue 

numerable sea fowl that remain on them during the breeding season. 
(See the Chapter on Manures.) 

According to Fourcroy and Vauquelin it contains a fourth part of 
its weight of uric acid, with ammonia and potash. 

The London and Edinburgh Philosophical Magazine, for July, 1841, 
contains a new analysis of the guano, made by M. Voelckel in the 
laboratory of Professor Wohler, and confirms what Klaprotli found, 
viz., that it contains, besides unchanged uric acid, a considerable quan- 
tity of two of its usual products of decomposition, viz. oxalic acid and 
ammonia. lUU parts of moist guano, contain, 

{Voelckel). (Klaproth ) 

Urate of ammonia, . . . 9.0 l6.0 

Oxalate of do. .... 10.6 

Do. of lime, .... 7.0 12.75 

Phosphate of ammonia, . . . 6.0 
Phosphate of ammonia and magnesia, 2.6 
Sulphate of potash, .... 5.5 

Do of soda, .... 3 8 common salt 0.05 

Chloride of ammonium, . . . 4.2 
Phosphate of lime, . . . 14.3 10.00 

Clay and sand, .... 4.7 32.00 

Undetermined organic substances,'] 
of which about 12 per cent, is sol- ( 32.3 28.75 

uble in water. A small quantity j 

of a soluble salt of iron. Water, J 

100.0 99.55 

Mr. J. H. Blake of Boston, who has recently visited Peru, informs 
me, that near Pabellon de Pica there is a high hill, the base of which, 
consisting chiefly of guano, is washed by the sea. From this bed, 
which is nearly a mile in length, and from 800 to 900 feet high, guano 
might be obtained at a cost, which would probably not e.xceed a cent 
and a half per pound, delivered in the United States. (See also Ap- 
pendix.) 
* Boussingault. Ann. de Ch. et de Phys. Ixv. p. 319. 



COMPOSITION OF EXCREMENTITIOUS MATTER. 97 

coloring matters of flowers. Nitrogen is not pre- 
sented to wild plants in any other form capable of 
assimilation. Ammonia, by its transformation, fur- 
nishes nitric acid to the tobacco plant, sun-flower, 
Chenopodium, and Borago officinalis, when they grow 
in a soil completely free from nitre. Nitrates are 
necessary constituents of these plants, which thrive 
only when ammonia is present in large quantity, and 
when they are also subject to the influence of the 
direct rays of the sun, an influence necessary to 
eff'ect the disengagement within their stem and 
leaves of the oxygen, which shall unite with the 
ammonia to form nitric acid. 

The urine of men and of carnivorous animals 
contains a large quantity of nitrogen, partly in the 
form of phosphates, partly as urea. Urea is con- 
verted during putrefaction into carbonate of ammo- 
nia, that is to say, it takes the form of the very salt 
which occurs in rain-water. Human urine is the 
most powerful manure for all vegetables containing 
nitrogen ; that of horses and horned cattle contains 
less of this element, but infinitely more than the 
solid excrements of these animals. In addition to 
urea, the urine of herbivorous animals contains hip- 
puric acid,* which is decomposed during putrefaction 
into benzoic acidf and ammonia. The latter enters 
into the composition of the gluten, but the benzoic 
acid often remains unchanged : for example, in the 
Anthoxanthiun odoratuni. 

The solid excrements of animals contain compar- 
atively very little nitrogen, but this could not be 
otherwise. The food taken by animals supports 
them only in so far as it offers elements for assimila- 
tion to the various organs which they may require 

* Rouelle announced the discovery of an acid in the urine of the 
horse, which he called benzoic, hut in 1834 Liebig sliowed that this was 
not benzoic acid, but one easily convertible into it, and distinguished it 
by the name hipptiric, from i/rn:oc, a horse, and ovqov, urine. 

f Benzoic acid exists in gum benzoin, &c. ; it is formed, according 
to Liebig, by the oxidation of a supposed base called henzule. Its 
composition is carbon 14, hydroo-en 5, oxygen 2. 

9 



98 SOURCE AND ASSIMILATION. OF NITROGEN. 

for their increase or renewal. Corn, grass, and all 
plants, without exception, contain azotized substan- 
ces.* The quantity of food which animals take for 
their nourishment, diminishes or increases in the 
same proportion as it contains more or less of the 
substances containing nitrogen. A horse may be' 
kept alive by feeding it with potatoes, which contain 
a very small quantity of nitrogen ; but life thus 
supported is a gradual starvation ; the animal in- 
creases neither in size nor strength, and sinks under 
every exertion. The quantity of rice which an 
Indian eats astonishes the European ; but the fact 
that rice contains less nitrogen than any other kind 
of grain at once explains the circumstance. f 

Now, as it is evident that the nitrogen of the 
plants and seeds used by animals as food must be 
employed in the process of assimilation, it is natural 
to expect that the excrements of these animals will 
be deprived of it in proportion to the perfect diges- 
tion of the food, and can only contain it when mixed 
with secretions from the liver and intestines. Under 
all circumstances, they must contain less nitrogen 
than the food. When, therefore, a field is manured 
with animal excrements, a smaller quantity of matter 

* The late Professor Gorhani obtained from Indian corn a substance 
to which he gave the name Zeiiic, according to whose analysis it con- 
tains no nitrogen ; but ammonia has since been obtained from it. 

t According to the analysis of Braconnot {Jinn, de Chim. et de Phys. 
t. iv. p. 370), this grain is thus constituted. 



Carolina rice. 


Piedmont rice. 


Water, . . . .5.00 


7.00 


Starch, .... 85.07 


83 80 


Parenchyma, . . .4.80 


4.80 


Gluten, . . . 3.60 


3.60 


Uncrystallizable sugar, 0.29 


0.05 


Gummy matter approach- ? a 71 
ing to starch, \ ' 


0.10 


Oil, .... 0.13 


0.25 


Phosphate of lime, . . 0.13 


0.40 



99.73 J 00.00. With tra- 

ces of muriate of potash, phosphate of potash, acetic acid, sulphur, 
and lime, and potash united to a vegetable alkali. 

Vauquelin was unable to detect any saccharine matter in rice. — 
Thomson's Organic Cheviistry, p. 883. 



FORM IN WHICH AMMONIA IS PRESENTED. 99 

containing nitrogen is added to it than has been 
taken from it in the form of grass, herbs, or seeds. 
By means of manure, an addition only is made to 
the nourishment which the air supplies. 

In a scientific point of view, it should be the care 
of the agriculturist so to employ all the substances 
containing a large proportion of nitrogen which his 
farm affords in the form of animal excrements, that 
they shall sserve as nutriment to his own plants. 
This will not be the case unless those substances 
are properly distributed upon his land. A heap of 
manure lying unemployed upon his land would serve 
him no more than his neighbors. The nitrogen in 
it would escape as carbonate of ammonia into the 
atmosphere, and a mere carbonaceous residue of 
decayed plants would, after some years, be found in 
its place. 

All animal excrements emit carbonic acid and 
ammonia, as long as nitrogen exists in them. In 
every stage of their putrefaction an escape of am- 
monia from them maybe induced by moistening them 
with a potash ley; the ammonia being apparent to 
the senses by a peculiar smell, and by the dense 
white vapor which arises when a solid body moist- 
ened with an acid is brought near it. This ammonia 
evolved from manure is imbibed by the soil either 
in solution in water, or in the gaseous form, and 
plants thus receive a larger supply of nitrogen than 
is afforded to them by the atmosphere. 

But it is much less the quantity of ammonia, 
yielded to a soil by animal excrements, than the 
form in which it is presented by them, that causes 
their great influence on its fertility. Wild plants 
obtain more nitrogen from the atmosphere in the 
form of ammonia than they require for their growth, 
for the water which evaporates through their leaves 
and blossoms, emits, after some time, a putrid smell, 
a peculiarity possessed only by such bodies as con- 
tain nitrogen. Cultivated plants receive the same 
quantity of nitrogen from the atmosphere as trees, 

L»rc. 



100 SOURCE AND ASSIMILATION OF NITROGEN. 

shrubs, and other wild plants; but this is not suffi- 
cient for the purposes of agriculture. Agriculture 
differs essentially from the cultivation of forests, 
inasmuch as its principal object consists in the pro- 
duction of nitrogen under any form capable of 
assimilation; whilst the object of forest culture is 
confined principally to the production of carbon. 
All the various means of culture are subservient to 
these two main purposes. A part only of the carbonate 
of ammonia which is conveyed by rain to the soil is 
received by plants, because a certain quantity of it 
is volatilized with the vapor of water; only that 
portion of it can be assimilated which sinks deeply 
into the soil, or which is conveyed directly to the 
leaves by dew, or is absorbed from the air along 
with the carbonic acid. 

Liquid animal excrements, such as the urine with 
which the solid excrements are impregnated, contain 
the greatest part of their ammonia in the state of 
salts, in a form, therefore, in which it has completely 
lost its volatility ; when presented in this condition, 
not the smallest portion of the ammonia is lost to 
the plants ; it is all dissolved by water, and imbibed 
by their roots. The evident influence of gypsum 
upon the growth of grasses — the striking fertility 
and luxuriance of a meadow upon which it is strewed 
— depends only upon its fixing in the soil the am- 
monia of the atmosphere, which would otherwise be 
volatilized, with the water which evaporates.* The 
carbonate of ammonia contained in rain-water is 
decomposed by gypsum, in precisely the same man- 
ner as in the manufacture of sal-ammoniac. Soluble 
sulphate of ammonia and carbonate of lime are 
formed; and this salt of ammonia possessing no 
volatility is consequently retained in the soil. All 
the gypsum gradually disappears, but its action upon 

* It has long been the practice in some parts of the country to strew 
the floors of stables with gypsum. This prevents the disagreeable odor 
arising from the putrefaction of stable manure, by decomposing the 
"jmmoniacal salts which are formed. — Ed. 



USE OF GYPSUM. 101 

the carbonate of ammonia continues as long as a 
trace of it exists. 

The beneficial influence of gypsum and of many- 
other salts has been compared to that of aroraatics, 
which increase the activity of the human stomach 
and intestines, and give a tone to the whole system. 
But plants contain no nerves ; we know of no sub- 
stance capable of exciting them to intoxication and 
madness, or of lulling them to sleep and repose. 
No substance can possibly cause their leaves to ap- 
propriate a greater quantity of carbon from the 
atmosphere, when the other constituents which the 
seeds, roots, and leaves require for their growth are 
wanting.* The favorable action of small quantities 
of aromatics upon man, when mixed with his food, 
is undeniable; but aromatics are given to plants 
loithout food to be digested, and still they flourish 
with greater luxuriance. 

It is quite evident, therefore, that the common 
view concerning the influence of certain salts upon 
the growth of plants evinces only ignorance of its 
cause. 

The action of gypsum or chloride of calcium really 
consists in their giving a fixed condition to the 
nitrogen — or ammonia which is brought into the 
soil, and which is indispensable for the nutrition of 
plants. 

In order to form a conception of the eff'ect of 

* In 1831, I suggested to a well known and most successful culti- 
vator (Mr. Haggerston), the application of a weak solution of chlorine 
gas to the soil in whicli plants were growing. It appeared to act 
merely as a stimulant, the plants flourished for a time with great lux- 
uriance, and in some the foliage was remarkable. The leaves of a 
Pelargonium (well known as the Washiiiaton Geranmm) attained the 
diameter of a foot, but the flowers were by no means equal to those 
of similar plants cultivated in the usual manner ; the plants soon 
perished. Probably a supply of nutriment proportioned to the increased 
demand was not supplied. 

The necessity for this supply is now well known, and Pelargoniums 
are now grown with great luxuriance and perfection, both of leaves 
and flowers, by the free use of ''manure water," obtained by steeping 
horsedung in rain-water. The soil, too, best adapted to the plants is 
chiefly prepared from decayed vegetable matter, derived from decom- 
posed leaves and plants, mi.'ced v^'ith that from the sods of fields. 

9* 



102 SOURCE AND ASSIMILATION OF NITROGEN. 

gypsum, it may be sufficient to remark, that 110 lbs. 
of burned gypsum fixes as much ammonia in the 
soil as 6887 lbs. of horse's urine* would yield to it, 
even on the supposition that all the nitrogen of the 
urea and hippuric acid were absorbed by the plants 
without the smallest loss, in the form of carbonate 
of ammonia. If we admit with Boussingaultf that 
the nitrogen in grass amounts to j^^ of its weight, 
then every pound of nitrogen which we add in- 
creases the produce of the meadow 110 lbs., and 
this increased produce of 110 lbs. is effected by the 
aid of a little more than 4 lbs. of gypsum. 

Water is absolutely necessary to effect the decom- 
position of the gypsum, on account of its difficult 
solubility, (1 part of gypsum requires 400 parts of 
water for solution,) and also to assist in the absorp- 
tion of the sulphate of ammonia by the plants : 
hence it happens, that the influence of gypsum is 
not observable on dry fields and meadows. In such 
it would be advisable to emplo}' a salt of more easy 
solubility, such as chloride of calcium. 

The decomposition of gypsum by carbonate of 
ammonia does not take place instantaneously; on 
the contrary, it proceeds very gradually, and this 
explains why the action of the gypsum lasts for 
several years. 

The advantage of manuring fields with burned 
clay, and the fertility of ferruginous soils, which 
have been considered as facts so incomprehensible, 
may be explained in an equally simple manner. 
They have been ascribed to the great attraction for 
water, exerted by dry clay and ferruginous earth ; 
but common dry arable land possesses this property 

* Thf urine of the horse contains, according to Fourcroy and Van- 
quelin, in 1000 parts, 

Urea ... 7 parts. 

Hippurate of soda . . 24 " 
Salts and water . . 979 " 

1000 parts, 
t Boussingault, Ann. de Ch. et de Phys., t. Ixiii. page 243. 



USE OF BURNED CLAY AS A MANURE. 103 

in as great a degree : and besides, what influence 
can be ascribed to a hundred pounds of water spread 
over an acre of land, in a condition in which it can- 
not be serviceable either by the roots or leaves ? 
The true cause is this : — 

The oxides of iron and alumina are distinguished 
from all other metallic oxides by their power of form- 
ing solid compounds with ammonia. The precipi- 
tates obtained by the addition of ammonia to salts 
of alumina or iron are true salts, in which the ammo- 
nia is contained as a base. Minerals containing alu- 
mina or oxide of iron also possess, in an eminent de- 
gree, the remarkable property of attracting ammonia 
from the atmosphere and of retaining it. Vauquelin, 
whilst enorasfed in the trial of a criminal case, discov- 
ered that all rust of iron contains a certain quantity of 
ammonia. Chevalier afterwards found that ammonia 
is a constituent of all minerals containing iron ; that 
even hematite, a mineral which is not at all porous, 
contains one per cent, of it. Bonis showed also, that 
the peculiar odor observed on moistening minerals 
containing alumina, is partly owing to their exhaling 
ammonia. Indeed, gypsum and some varieties of 
alumina, pipe-clay for example, emit so much ammo- 
nia, when moistened with caustic potash, that even 
after they have been exposed for two days, reddened 
litmus paper held over them becomes blue. Soils, 
therefore, which contain oxides of iron, and burned 
clay, must absorb ammonia, an action which is fa- 
vored by their porous condition ; they further pre- 
vent the escape of the ammonia once absorbed, by 
their chemical properties. Such soils, in fact, act 
precisely as a mineral acid would do, if extensively 
spread over their surface; with this difference, that 
the acid would penetrate the ground, enter into com- 
bination with lime, alumina, and other bases, and 
thus lose, in a few hours, its property of absorbing 
ammonia from the atmosphere. The addition of 
burned clay to soils has also a secondary influence ; 



104 SOURCE AND ASSIMILATION OF NITROGEN. 

it renders the soil porous, and, therefore, more per- 
meable to air and moisture. 

The ammonia absorbed by the clay or ferruginous 
oxides is separated by every shower of rain, and 
conveyed in solution to the soil. 

Powdered charcoal possesses a similar action, but 
surpasses all other substances in the power which it 
possesses of condensing ammonia within its pores, 
particularly when it has been previously heated to 
redness. Charcoal absorbs 90 times its volume of 
ammoniacal gas, which may be again separated by 
simply moistening it with water. (De Saussure.) 
Decayed wood approaches very nearly to charcoal in 
this power ; decayed oak wood absorbs 72 times its 
volume, after having been completely dried under 
the air-pump.* We have here an easy and satisfac- 
tory means of explaining still further the properties 
of humus, or wood in a decaying state. It is not 
only a slow and constant source of carbonic acid, 
but it is also a means by which the necessary nitro- 
gen is conveyed to plants. 

Nitrogen is found in lichens, which grow on basal- 
tic rocks. Our fields produce more of it than we 
have given them as manure, and it exists in all kinds 
of soils and minerals which were never in contact 
with organic substances. The nitrogen in these cases 
could only have been extracted from the atmosphere. 

We find this nitrogen in the atmosphere in rain 
water and in all kinds of soils, in the form of ammo- 
nia, as a product of the decay and putrefaction of 
preceding generations of animals and vegetables. 
We find likewise that the proportion of azotized mat- 
ters in plants is augmented by giving them a larger 
supply of ammonia conveyed in the form of animal 
manure. 

No conclusion can then have a better foundation 

* In experiments instituted by Dr. Daubeny, with a view of ascer- 
taining whether vegetable mould had not the same property, he found 
that both carbonic acid and ammoniacal gases were condensed within 
its pores, as thej' would be by a lump of charcoal. 



OF THE INORGANIC CONSTITUENTS OF PLANTS 105 

than this, that it is the ammonia of the atmosphere 
which furnishes nitrogen to plants,* 

Carbonic acid, water, and ammonia, contain the 
elements necessary for the support of animals and 
vegetables. The same substances are the ultimate 
products of the chemical processes of decay and pu- 
trefaction. All the innumerable products of vitality 
resume, after death, the original form from which 
they sprung. And thus death, — the complete dis- 
solution of an existing generation, — becomes the 
source of life for a new one. 



CHAPTER VI. 

OF THE INORGANIC CONSTITUENTS OF PLANTS. 

Carbonic acid, water, and ammonia, are necessary 
for the existence of plants, because they contain the 
elements from which their organs are formed; but 
other substances are likewise requisite for the for- 
mation of certain organs destined for special func- 
tions peculiar to each family of plants. Plants ob- 
tain these substances from inorganic nature. In the 
ashes left after the incineration of plants, the same 
substances are found, although in a changed con- 
dition. 

Although the vital principle exercises a great pow- 
er over chemical forces, yet it does so only by direct- 
ing the way in which they are to act, and not by 
changing the laws to which they are subject. Hence 
when the chemical forces are employed in the pro- 
cesses of vegetable nutrition, they must produce the 
same results which are observed in ordinary chemical 
phenomena. The inorganic matter contained in plants 

* From some experiments with respect to the action of light upon 
plants, Or Daubeny is inclined to suspect that in some cases hydro- 
gen is assimilated whilst nitrogen is disengaged. See his. Memoir in 
Pkilus. Trans. 183C. 



106 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

must, therefore, be subordinate to the laws which 
regulate its combinations in common chemical pro- 
cesses. 

The most important division of inorganic substan- 
ces is that of acids and alkalies. Both of these have 
a tendency to unite together, and form neutral com- 
pounds, which are termed salts. According to the 
doctrine of equivalents, these combinations are al- 
ways effected in definite proportions, that is to say, 
one equivalent of an acid always unites with one or 
two equivalents of a base, whatever that base may 
be. Thus 501-17 parts by weight of sulphuric acid 
unite with 1 eq. of potash, and form 1 eq. of sulphate 
of potash ; the same quantity unites with 1 eq. of 
soda, and produces sulphate of soda. From this 
fact follows the rule, — that the quantity, which an 
acid requires of an alkali for its saturation, may be 
represented by a very simple number. 

It is perfectly necessary to form a proper concep- 
tion of what chemists denominate the " capacity 
for saturation of an acid," before we are able to 
form a correct idea of the functions performed in 
plants, by their inorganic constituents. The power 
of a base to neutralize an acid does not- depend 
upon the quantity of radical which it contains, but 
altogether upon the quantity of its oxygen. Thus 
protoxide of iron contains 1 eq. of oxygen, and 
unites with 1 eq. of sulphuric acid in forming a 
neutral salt ; but peroxide of iron contains 3 eq. of 
oxygen, and requires 3 eq. of the same acid for its 
neutralization. Hence when a given weight of an 
acid is neutralized by different bases, the quantity 
of oxygen contained in these bases must be the 
same as is exhibited by the following scale : — 

501*17 parts of Sulphuric Acid neutralize S.jS-.jS Magnesia Oxygen = 100 
" " " 64.729 Strontia " =100 

" " " 1451-61 Oxide of Silver " =100 

" " " 956-8 Barytes " = 100 

It follows from the law of equivalents, that the 
quantity of oxygen in a base must stand in a simple 
relation to the quantity of oxygen in an acid which 



IMPORTANCE OF ALKALINE BASES. 107 

unites with it. By this is meant, that the quantities 
in both cases must either be equal or multiples of 
each other ; for the doctrine of equivalents denies 
the possibility of their uniting in fractional parts. 
This will be rendered obvious by a consideration of 
the two following examples : 

100 parts of Cyanic Acid contain 23 26 oxygen = 1. 

100 parts of Cyanic Acid saturate 137-21 parts of potash, which contain 

23 26 oxygen = i . 
100 parts of Nitric Acid contain 73-85 oxygen =5. 
100 parts of Nitric Acid saturate 214-40 parts of oxide of silver, which 

contain 1477 oxygen = 1. 

In the first of these cases, the relation of the 
oxygen of the base to that of the acid is as 1 : 1 ; in 
the second, as 1 : 5. The capacity for saturation 
of each acid is, therefore, the constant quantity of 
oxygen necessary to neutralize 100 parts of it. 

Many of the inorganic constituents vary accord- 
ing to the soil in which the plants grow, but a cer- 
tain number of them are indispensable to their de- 
velopment. All substances in solution in a soil 
are absorbed by the roots of plants, exactly as a 
sponge imbibes a liquid, and all that it contains, 
wathout selection. The substances thus conveyed 
to plants are retained in greater or less quantity, or 
are entirely separated w^hen not suited for assimi- 
lation. 

Phosphate of magnesia in combination with am- 
monia is an invariable constituent of the seeds of 
all kinds of grasses. It is contained in the outer 
horny husk, and is introduced into bread along with 
the flour, and also into beer. The bran of flour con- 
tains the greatest quantity of it. It is this salt 
which forms large crystalline concretions, often 
amounting to several pounds in weight, in the ccBcuni 
of horses belonging to millers ; and when ammonia 
is mixed with beer, the same salt separates as a 
white precipitate. 

Most plants, perhaps all of them, contain organic 
acids of very diff'erent composition and properties, 
all of which are in combination with bases, such as 



108 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

potash, soda, lime, or magnesia. These bases evi- 
dently regulate the formation of the acids, for the 
diminution of the one is followed by a decrease of 
the other : thus in the grape, for example, the quan- 
tity of potash contained in its juice is less when 
it is ripe than when unripe ; and the acids, under 
the same circumstances, are found to vary in a simi- 
lar manner. Such constituents exist in small quan- 
tity in those parts of a plant in which the process 
of assimilation is most active, as in the mass of 
woody fibre ; and their quantity is greater in those 
organs whose office it is to prepare substances con- 
veyed to them for assimilation by other parts. The 
leaves contain more inorganic matters than the 
branches, and the branches more than the stem. 
The potato plant contains more potash before blos- 
soming than after it. 

The acids found in the different families of plants 
are of various kinds ; it cannot be supposed that 
their presence and peculiarities are the result of 
accident. The fumaric and oxalic acids in the liver- 
wort, the kinovic acid in the China nova, the ro- 
cellic acid in the Rocella tinctoria, the tartaric acid 
in grapes, and the numerous other organic acids, 
must serve some end in vegetable life. But if these 
acids constantly exist in vegetables, and are neces- 
sary to their life, which is incontestable, it is equally 
certain that some alkaline base is also indispensable, 
in order to enter into combination with the acids 
which are always found in the state of salts. All 
plants yield by incineration ashes containing car- 
bonic acid ; all therefore must contain salts of an 
organic acid.* 

Now, as we know the capacity of saturation of 
organic acids to be unchanging, it follows that the 
quantity of the bases united with them cannot vary, 
and for this reason the latter substances ought to 

* Salts of organic acids yield carbonates on incineration, if they 
contain either alkaline or earthy bases. 



INVARIABLE QUANTITY OF ALKALINE BASES. 109 

be considered with the strictest attention both by 
the agriculturist and physiologist. 

We have no reason to believe that a plant in a 
condition of free and unimpeded growth produces 
more of its peculiar acids than it requires for its 
own existence; hence, a plant, on whatever soil it 
grows, must contain an invariable quantity of alka- 
line bases. Culture alone will be able to cause a 
deviation. 

In order to understand this subject clearly, it will 
be necessary to bear in mind that any one of the 
alkaline bases may be substituted for another, the 
action of all being the same. Our conclusion is 
therefore by no means endangered by the existence 
of a particular alkali in one plant, which may be 
absent in others of the same species. If this in- 
ference be correct, the absent alkali or earth must 
be supplied by one similar in its mode of action, or 
in other words, by an equivalent of another base. 
The number of equivalents of these various bases 
which may be combined with a certain portion of 
acid must necessarily be the same, and therefore the 
amount of oxygen contained in them must remain 
unchanged under all circumstances and on whatever 
soil they grow. 

Of course, this argument refers only to those 
alkaline bases which in the form of organic salts 
form constituents of the plants. Now, these salts 
are preserved in the ashes of plants as carbonates, 
the quantity of which can be easily ascertained. 

It has been distinctly shown, by the analysis of 
De Saussure and Berthier, that the nature of a soil 
exercises a decided influence on the quantity of the 
diff'erent metallic oxides contained in the plants 
which grow on it ; that magnesia, for example, was 
contained in the ashes of a pine-tree grown at Mont 
Breven, whilst it was absent from the ashes of a 
tree of the same species from Mont La Salle, and 
that even the proportion of lime and potash was 
very different. 

10 



110 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

Hence it has been concluded, (erroneously, I be- 
lieve,) that the presence of bases exercises no par- 
ticular influence upon the growth of plants : but 
even were this view correct, it must be considered 
as a most remarkable accident that these same 
analyses furnish proof for the very opposite opinion. 
For although the composition of the ashes of these 
pine-trees was so very different, they contained, 
according to the analyses of De Saussure, an equal 
number of equivalents of metallic oxides; or, what 
is the same thing, the quantity of oxygen contained 
in all the bases was in both cases the same. 

100 parts of the ashes of the pine-tree from Mont 
Breven contained — 

Carbonate of Potash . 3G0 Quantity of oxygen in the Potash 0"41 
" Lime . 46-34 « " » Lime 7-33 

« Magnesia 6-77 " " " Magnesia 1-27 



Sum of the carbonates 56-71 Sum of the oxygen in the bases 9-01 

100 parts of the ashes of the pine from Mont La 
Salle contained* — 

Carbonate of Potash . 7-36 Quantity of oxygen in the Potash 0.85 
" Lime . 51-19 " » " Lime 8-10 

" Magnesia 00-00 

Sum of the carbonates 58-55 Sum of the oxygen in the bases 8-95 

The numbers 9-01 and 8-95 resemble each other 
as nearly as could be expected even in analyses 
made for the very purpose of ascertaining the fact 
above demonstrated, which the analyst in this case 
had not in view. 

Let us now compare Berthier's analyses of the 
ashes of two fir-trees, one of which grew in Norway, 
the other in Allevard (department de I'Isere). One 
contained 50, the other 25 per cent, of soluble salts. 
A greater difference in the proportion of the alkaline 
bases could scarcely exist between two totally dif- 

* According to the experiments of Saussure, 1000 parts of the wood of 
ihe pine from Mont Breven gave 11-S7 parts of ashes; the same quan- 
tity of wood from Mont La Salle yielded 11-28 parts. From this we 
might conclude that tlie two pines, although brought up in different 
soils, yet contained the same quantity of inorganic elements. 



INVARIABLE QUANTITY OF ALKALINE BASES. HI 

ferent plants, and yet even here the quantity of 
oxygen in the bases of both was the same, 

100 parts of the ashes of firwood from Allevard 
contained, according to Berthier, (Ann. de Chim. et 
de Phys. t, xxxii. p. 248,) 

Potash and Soda 16-8 in which 3-42 parts must be oxygen. 
Lime 29-5 " 8-20 « " 

Magnesia . 32 " 1.20 " " 



49-5 12-82 

Only part of the potash and soda in these ashes 
was in combination with organic acids ; the remain- 
der was in the form of sulphates, phosphates, and 
chlorides. One hundred parts of the ashes contain 
3-1 sulphuric acid, 4-2 phosphoric acid, and 0-3 hy- 
drochloric acid, which together neutralize a quantity 
of base containing 1-20 oxygen. This number there- 
fore must be subtracted from 12-82. The remainder 
11-62 indicates the quantity of oxygen in the alka- 
line bases, combined with organic acids in the fir- 
wood of Allevard. 

The firwood of Norway contained in 100 parts,* — 

Potash . 14-1 of which 2-4 parts would be oxygen. 

Soda . 20-7 " 5-3 " " 

Lime . 12-3 " 3-45 " " 

Magnesia 435 " 1-69 " " 



51-4.5 1284 

And if the quantity of oxygen of the bases in com- 
bination with sulphuric and phosphoric acid, viz. 
1-37, be again subtracted from 12-84, 11-47 parts 
remain as the amount of oxygen contained in the 
bases which were in combination with organic acids. 
These remarkable approximations cannot be acci- 
dental ; and if further examinations confirm them 
in other kinds of plants, no other explanation than 
that already given can be adopted. 

* This calculation is e.vact only in the case where the quantity of 
ashes is equal in weight for a given quantity of wood ; the difference 
cannot, however, be admitted to be so great as to change sensibly the 
above proportions. Berthier has not mentioned the proportion of ashes 
contained in the wood. 



112 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

It is not known in what form silica, manganese, 
and oxide of iron, are contained in plants ; but we 
are certain that potash, soda, and magnesia, can be 
extracted from all parts of their structure in the 
form of salts of organic acids. The same is the 
case with lime, when not present as insoluble oxalate 
of lime. It must here be remembered, that in plants 
yielding oxalic acid, the acid and potash never exist 
in the form of a neutral or quadruple salt, but always 
as a double acid salt, on whatever soil they may 
grow. The potash in grapes also, is more frequently 
found as an acid salt, viz. cream of tartar (bitartrate 
of potash), than in the form of a neutral compound. 
As these acids and bases are never absent from 
plants, and as even the form in which they present 
themselves is not subject to change, it may be 
affirmed that they exercise an important influence 
on the development of the fruits and seeds, and also 
on many other functions of the nature of which we 
are at present ignorant. 

The quantity of alkaline bases existing in a plant 
also depends evidently on this circumstance of their 
existing only in the form of acid salts, — for the 
capacity of saturation of an acid is constant; and 
when we see oxalate of lime in the lichens occupy- 
ing the place of w^oody fibre which is absent, we 
must regard it as certain that the soluble organic 
salts are destined to fulfil equally important though 
diiferent functions, so much so that we could not 
conceive the complete development of a plant with- 
out their presence, that is, without the presence of 
their acids, and consequently of their bases. 

From these considerations we must perceive, that 
exact and trustworthy examinations of the ashes of 
plants of the same kind growing upon different soils 
would be of the greatest importance to vegetable 
physiology, and would decide whether the facts 
above mentioned are the results of an unchanging 
law for each family of plants, and whether an inva- 
riable number can be found to express the quantity 



SUBSTITUTION OF ALKALINE BASES. 113 

of oxygen which each species of plant contains in 
the bases united with organic acids. In all proba- 
bility such inquiries will lead to most important 
results ; for it is clear that if the production of a 
certain unchanging quantity of an organic acid is 
required by the peculiar nature of the organs of a 
plant, and is necessary to its existence, then potash 
or lime must be taken up by it in order to form salts 
with this acid ; that if these do not exist in suffi- 
cient quantity in the soil, other bases must supply 
their place ; and that the progress of a plant must 
be wholly arrested Avhen none are present. 

Seeds of the Salsola Kali, when sown in common 
garden soil, produce a plant containing both potash 
and soda ; while the plants grown from the seeds of 
this contain only salts of potash, with mere traces 
of muriate of soda. (Cadet.) 

The examples cited above, in which the quantity 
of oxygen contained in the bases was shown to be 
the same, lead us to the legitimate conclusion, that 
the development of certain plants is not retarded 
by the substitution of the bases contained in them. 
But it was by no means inferred that any one base 
could replace all the others, which are found in a 
plant in its normal condition. On the contrary, it 
is known that certain bases are indispensable for the 
growth of a plant, and these could not be substituted 
without injuring its development. Our inference has 
been drawn from certain plants, which can bear 
without injury this substitution ; and it can only be 
extended to those plants which are in the same con- 
dition. It will be shown afterwards that corn or 
vines can only thrive on soils containing potash, and 
that this alkali is perfectly indispensable to their 
growth. Experiments have not been sufficiently 
multiplied so as to enable us to point out in what 
plants potash or soda may be replaced by lime or 
magnesia ; we are only warranted in affirming that 
such substitutions are in many cases common. The 
ashes of various kinds of plants contain very differ- 
10* 



114 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

ent quantities of alkaline bases, such as potash, soda, 
lime, or magnesia. When lime exists in the ashes 
in large proportion, the quantity of magnesia is di- 
minished, and in like manner according as the latter 
increases the lime or potash decreases. In many kinds 
of ashes not a trace of magnesia can be detected. 

The existence of vegetable alkalies in combination 
with organic acids gives great weight to the opinion, 
that alkaline bases in general are connected with 
the development of plants. 

If potatoes are grown where they are not supplied 
with earth, the magazine of inorganic bases, (in 
cellars, for example,) a true alkali, called Solanin, 
of very poisonous nature, is formed in the sprouts 
which extend towards the light, while not the small- 
est trace of such a substance can be discovered in 
the roots, herbs, blossoms, or fruits of potatoes 
grown in fields. (Otto.)* In all the species of the 
Cinchona, kinic acid is found ; but the quantity of 
quinia, cinchonina, and lime, which they contain is 
most variable. From the fixed bases in the products 
of incineration, however, we may estimate pretty 
accurately the quantity of the peculiar organic bases. 
A maximum of the first corresponds to a minimum of 
the latter, as must necessarily be the case if they 
mutually replace one another according to their 
equivalents. We know that different kinds of opium 
contain meconic acid in combination with very dif- 
ferent quantities of narcotina," morphia, codeia, &c., 
the quantity of one of these alkaloids diminishing 
on the increase of the others. Thus the smallest 



The analysis of potatoes afforded M. Henry 

Starch 13.30 

Water 73.12 

Albumen . . . . . . . . 92 

Uncrystallizable sugar ..... 3.30 

Volatile poisonous matter .... 0.05 

Peculiar fatty matter ..... 1.12 

Parenchyma ....... 6.79 

Malic acid and salts 1.40 

100.00 



EXCREMENTS OF PLANTS. 115 

quantity of morphia is accompanied Ly a maximum 
of narcotina. Not a ti'ace of meconic acid* can be 
discovered in many kinds of opium, but there is not 
on this account an absence of acid, for the meconic 
is here replaced by sulphuric acid. Here, also, we 
have an example of what has been before stated, for 
in those kinds of opium where both these acids ex- 
ist, they are always found to bear a certain relative 
proportion to one another. Attention to these facts 
must be very important in the selection of soils des- 
tined for the cultivation of plants which yield the 
vegetable alkaloids. 

Now if it be found, as appears to be the case in 
the juice of poppies, that an organic acid may be re- 
placed by an inorganic, without impeding the growth 
of a plant, we must admit the probability of this sub- 
stitution taking place in a much higher degree in the 
case of the inorganic bases. 

When roots find their more appropriate base in 
sufficient quantity, they will take up less of another. 

These phenomena do not show themselves so fre- 
quently in cultivated plants, because they are sub- 
jected to special external conditions for the purpose 
of the production of particular constituents or par- 
ticular organs. 

When the soil, in which a white hyacinth is grow- 
ing in a state of blossom, is sprinkled with the juice 
of the Phytolacca decandra,f the white blossoms as- 
sume in one or two hours a red color, which again 
disappears after a few days under the influence of 
sunshine, and they become white and colorless as 
before. I The juice in this case evidently enters into 
all parts of the plant, without being at all changed 
in its chemical nature, or without its presence being 
apparently either necessary or injurious. But this 

* Robiquet did not obtain a trace of meconate of lime from 300 lbs. 
of opium, whilst in other kinds the quantity was very considerable. 
£nn. de C'liim. liii. p. 425. 

t American nightshade. 

I Biot, in the Comptes rendus des Siances de V Acadimie des Sciences, 
ii Paris, ler Simestre, 1837, p. 12. 



116 OF THE INOKGANIC CONSTITUENTS OF PLANTS. 

condition is not permanent, and Avhen the blossoms 
have again become colorless, none of the coloring 
matter remains ; and if it should occur that any of 
its elements were adapted for the purposes of nutri- 
tion of the plant, then these alone would be retained, 
whilst the rest would be excreted in an altered form 
by the roots. 

Exactly the same thing must happen when we 
sprinkle a plant with a solution of chloride of potas- 
sium, nitre, or nitrate of strontia ; they will enter 
into the different parts of the plant, just as the col- 
ored juice mentioned above, and will be found in 
its ashes if it should be burnt at this period. Their 
presence is merely accidental; but no conclusion can 
be hence deduced against the necessity of the pres- 
ence of other bases in plants. The experiments of 
Macaire-Princep have shown, that plants made to 
vegetate with their roots in a weak solution of ace- 
tate of lead, and then in rain-water, yield to the lat- 
ter all the salt of lead which they had previously ab- 
sorbed. They return, therefore, to the soil all mat- 
ters which are unnecessary to their existence. Again, 
when a plant, freely exposed to the atmosphere, rain, 
and sunshine, is sprinkled with a solution of nitrate 
of strontia, the salt is absorbed, but it is again sep- 
arated by the roots and removed further from them 
by every shower of rain, which moistens the soil, so 
that at last not a trace of it is to be found in the 
plant. 

Let us consider the composition of the ashes of 
two fir-trees as analyzed by an acute and most accu- 
rate chemist. One of these grew in Norway, on a 
soil the constituents of which never changed, but to 
which soluble salts, and particularly common salt, 
were conveyed in great quantity by rain-water. How 
did it happen that its ashes contained no appreciable 
trace of salt, although we are certain that its roots 
must have absorbed it after every shower ? 

We can explain the absence of salt in this case by 
means of the direct and positive observations refer- 



EXCREMENTS OF PLANTS. 117 

red to, which have shown that plants have the power 
of returning to the soil all substances unnecessary 
to their existence J and the conclusion to which all 
the foregoing facts lead us, when their real value and 
bearing are apprehended, is that the alkaline bases 
existing in the ashes of plants must be necessary to 
their growth, since if this were not the case they 
would not be retained. 

The perfect development of a plant, according to 
this view, is dependent on the presence of alkalies 
or alkaline earths ; for when these substances are 
totally wanting its growth will be arrested, and when 
they are only deficient it must be impeded. 

In order to apply these remarks, let us compare 
two kinds of trees, the wood of which contains une- 
qual quantities of alkaline bases, and we shall find 
that one of these grows luxuriantly in several soils 
upon which the others are scarcely able to vegetate. 
For example, .10,000 parts of oak-wood yield 250 
parts of ashes, the same quantity of fir-wood only 
83, of linden-wood 500, of rye 440, and of the herb 
of the potato-plant 1500 parts.* 

Firs and pines find a sufficient quantity of alkalies 
in granitic and barren sandy soils in which oaks will 
not grow ; and wheat thrives in soils favorable for 
the linden-tree, because the bases which are neces- 
sary to bring it to complete maturity, exist there in 
sufficient quantity. The accuracy of these conclu- 
sions, so highly important to agriculture and to the 
cultivation of forests, can be proved by the most 
evident facts. 

All kinds of grasses, the Equisef.ace(B, for exam- 
ple, contain in the outer parts of their leaves and 
stalk a large quantity of silicic acid and potash in 
the form of acid silicate of potash. The proportion 
of this salt does not vary perceptibly in the soil of 
corn-fields, because it is again conveyed to them as 
manure in the form of putrefying straw. But this is 

* Berthier, ^nnales de Cliimie et de Physique, t. xxx. p. 248. 



118 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

not the case in a meadow, and hence we never find a 
luxuriant crop of grass * on sandy and calcareous 
soils, which contain little potash, evidently because 
one of the constituents indispensable to the growth 
of the plants is wanting. Soils formed from basalt, 
grauwacke, and porphyry, are, ccetej^is paribus, the 
best for meadow-land, on account of the quantity of 
potash which enters into their composition. The 
potash abstracted by the plants is restored during 
the annual irrigation. The potash contained in the 
soil itself is inexhaustible in comparison with the 
quantity removed by plants. But when we increase 
the crop of grass in a meadow by means of gypsum, 
we remove a greater quantity of potash with the hay 
than can under the same circumstances be restored. 
Hence it happens that, after the lapse of several 
years, the crops of grass on the meadows manured 
with gypsum diminish, owing to the deficiency of 
potash. But if the meadow be strewed from time to 
time with wood-ashes, even with the lixiviated ashes 
which have been used by soap-boilers, (in Germany 
much soap is made from the ashes of wood,) then 
the grass thrives as luxuriantly as before. The ash- 
es are only a means of restoring the potash, f 

* It would be of importance to examine what alkalies are contained 
in the ashes of the seashore plants which grow in the humid hollows 
of downs, and especially in those of the millet-grass. If potash is not 
found in them, it must certainly be replaced by soda as in the Salsola, 
or by lime as in the Plurabaainea. — L. 

t The compost which has been employed with most advantage as a 
top dressing to grass by Mr. Haggerston, on the estate of J. P. Gushing, 
Esq., at Watertown, is prepared from peat and barilla alone. 

The peat previously cut and dried is made into heaps with alternate 
layers of barilla, tlie thickness of each layer of peat being eight inches, 
and of the barilla four inches. This heap is allowed to remain undis- 
turbed during the winter, in the spring it is carefully turned and then 
allowed to remain until the ensuing autumn, when it is spread upon 
the land. 

Peat which is to be ploughed into the land, having been deposited in 
the yard to which swine have free access, is mixed with stable manure 
in the proportion of two thirds peat to one third manure. 

Barilla is the crude soda which is imported from Spain, Sicily, &c., 
where it is prepared by burning the plant called salsola soda. Accord- 
ing to Dr. Ure it contains 20 per cent, of real alkali (soda) with muri- 
ates and sulphates of soda, some lime and alumina, with very little 
sulphur. 



REPLACEMENT OF EXHAUSTED ALKALIES. 119 

A harvest of grain is obtained every thirty or forty 
years from the soil of the Luneburg heath, by strew- 
ing it with the ashes of the heath-plants {Erica vul- 
garis) which grow on it. These plants during the 
long period just mentioned collect the potash and 
soda, which are conveyed to them by rain-water ; 
and it is by means of these alkalies that oats, barley, 
and rye, to which they are indispensable, are ena- 
bled to grow on this sandy heath. 

The woodcutters in the vicinity of Heidelberg have 
the privilege of cultivating the soil for their own use, 
after felling the trees used for making tan. Before 
sowing the land thus obtained, the branches, roots, 
and leaves, are in every case burned, and the ashes 
used as a manure, which is found to be quite indis- 
pensable for the growth of the grain. The soil itself 
upon which the oats grow in this district consists of 
sandstone ; and although the trees find in it a quan- 
tity of alkaline earths sufficient for their own suste- 
nance, yet in its ordinary condition it is incapable 
of producing grain. 

The most decisive proof of the use of strong 
manure was obtained at Bingen (a town on the 
Rhine), w^here the produce and development of vines 
were highly increased by manuring them with such 
substances as shavings of horn, &c. ; but after some 
years the formation of the wood and leaves de- 
creased to the great loss of the possessor, to such 
a degree that he has long had cause to regret his 
departure from the usual methods. By the manure 
employed by him, the vines had been too much 
hastened in their growth; in two or three years 
they had exhausted the potash in the formation of 
their fruit, leaves, and wood, so that none remained 
for the future crops, his manure not having con- 
tained any potash. 

There are vineyards on the Rhine the plants of 
which are above a hundred years old, and all of 
these have been cultivated by manuring them with 
cow-dung, a manure containing a large proportion 



120 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

of potash, although very little nitrogen. All the 
potash, in fact, which is contained in the food con- 
sumed by a cow is again immediately discharged in 
its excrements. 

The experience of a proprietor of land in the 
vicinity of Gottingen offers a most remarkable ex- 
ample of the incapability of a soil to produce wheat 
or grasses in general, when it fails in any one of 
the materials necessary to their growth. In order 
to obtain potash, he planted his whole land with 
wormwood, the ashes of which are well known to 
contain a large proportion of the carbonate of that 
alkali. The consequence was, that he rendered his 
land quite incapable of bearing grain for many years, 
in consequence of having entirely deprived the soil 
of its potash. 

The leaves and small branches of trees contain 
the most potash; and the quantity of them which is 
annually taken from a wood, for the purpose of 
being employed as litter,* contains more of that alkali 
than all the old wood which is cut down. The bark 
and foliage of oaks, for example, contain from 6 to 
9 per cent, of this alkali; the needles of firs and 
pines, 8 per cent. 

With every 2920 lbs. of firwood which are yearly 
removed from an acre of forest, only from 0-125 to 
0-58 lbs. of alkalies are abstracted from the soil, 
calculating the ashes at 0*83 per cent. The moss, 
however, which covers the ground, and of which the 
ashes are known to contain so much alkali, con- 
tinues uninterrupted in its growth, and retains that 
potash on the surface, which would otherwise so 
easily penetrate with the rain through the sandy 
soil. By its decay, an abundant provision of alkalies 

* This refers to a custom some time since very prevalent in Ger- 
many, altliouffli now discontinued. The leaves and small twigs of 
trees were gleaned from the forests by poor people, for the purpose 
of being used as litter for their cattle. The trees, however, were 
found to suffer so much in consequence, that their removal is now 
strictly prohibited. The cause of the injury was that stated in the 
text. — Ed.] 



NECESSITY OF CERTAIN CONDITIONS FOR NUTRITION. 121 

is supplied to the roots of the trees, and a fresh 
supply is rendered unnecessary. 

The supposition of alkalies, metallic oxides, or in- 
organic matter in general, being produced by plants, 
is entirely refuted by these well-authenticated facts. 

It is thought very remarkable, that those plants 
of the grass tribe, the seeds of which furnish food 
for man, follow him like the domestic animals. But 
saline plants seek the seashore or saline springs, 
and the Chenopodium the dunghill from similar 
causes. Saline plants require common salt, and the 
plants which grow only on dunghills need ammonia 
and nitrates, and they are attracted whither these 
can be found, just as the dung-fly is to animal ex- 
crements. So likewise none of our corn-plants can 
bear perfect seed§, that is, seeds yielding flour, 
without a large supply of phosphate of magnesia and 
ammonia, substances which they require for their 
maturity. And hence, these plants grow only in a 
soil where these three constituents are found com- 
bined, and no soil is richer in them than those 
where men and animals dwell together ; where the 
urine and excrements of these are found corn-plants 
appear, because their seeds cannot attain maturity un- 
less supplied with the constituents of those matters. 

When we find sea-plants near our salt-works, 
several hundred miles distant from the sea, we know 
that their seeds have been carried there in a very 
natural manner, namely, by wind or birds, which 
have spread them over the whole surface of the 
earth, although they grow only in those places in 
which they find the conditions essential to their life. 

Numerous small fish, of not more than two inches 
in length ( Gasterosteiis aciileatus), are found in the 
salt-pans of the graduating house at Nidda (a vil- 
lage in Hesse Darmstadt). No living animal is found 
in the salt-pans of Neuheim, situated about 18 miles 
from Nidda ; but the water there contains so much 
carbonic acid and lime, that the walls of the gradu- 
ating house are covered with stalactites. Hence 
11 



122 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

the eggs conveyed to this place by birds do not 
find the conditions necessary for their development, 
which they found in the former place.* 

How much more wonderful and inexplicable does 
it appear, that bodies which remain fixed in the 
strong heat of a fire, have under certain conditions 
the property of volatilizing,and, at ordinary tempera- 
tures, of passing into a state, of which we cannot 
say whether they have really assumed the form of a 
gas or are dissolved in one ; Steam or vapors in 
general have a very singular influence in causing 
the volatilization of such bodies, that is, of causing 
them to assume the gaseous form. A liquid during 
evaporation communicates the power of assuming 
the same state in a greater or less degree to all sub- 
stances dissolved in it, although they do not of 
themselves possess that propel-ty. 

Boracic acidf is a substance which is completely 
fixed in the fire ; it suffers no change of weight ap- 
preciable by the most delicate balance, when ex- 
posed to a white heat, and, therefore, it is not 
volatile. Yet its solution in water cannot be evap- 
orated by the gentlest heat, without the escape of a 
sensible quantity of the acid with the steam. Hence 
it is that a loss is always experienced in the analysis 
of minerals containing this acid, when liquids in 

* The itch-insect (Acarus Scabiei) is considered by Burdach as the 
production of a morbid condition, so likewise lice in children ; the 
original generation of the fresh-water muscle (mytilus) in fish-ponds, 
of sea-plants in the vicinity of salt-works, of nettles and grasses, of 
fish in pools of rain, of trout in mountain streams, &c., is according to 
the same natural philosopher not impossible. A soil consisting of 
crumbled rocks, decayed vegetables, rain and salt water, &c , is here 
supposed to possess the power of generating shell fish, trout, and salt- 
wort (suJicorvia). All inquiry is arrested by such opinions, when 
propag;ited by a teacher who enjoys a merited reputation, obtained by 
knowledge and hard labor. These subjects, however, have hitherto 
met with the most superficial observation, although they well merit 
strict investigation. The dark, the secret, the mysterious, the enigmatic, 
is, in fact, too seducing for the youthful and philosophic mind, which 
would penetrate tlie deepest depllis of nature, without the assistance 
of the shaft or ladder of the miner. This is poetrj', but not sober 
philosophical inquiry. 

t The acid from borax. 



INORGANIC ORIGIN OF AMMONIA- 123 

which it is dissolved are evaporated. The quantity 
of boracic acid v^^hich escapes with a cubic foot of 
steam, at the temperature of boiling water, cannot 
be detected by our most sensible re-agents; and 
nevertheless the many hunired tons annually brought 
from Italy as an article of commerce, are procured 
by the uninterrupted accumulation of this apparently 
inappreciable quantity. The hot steam which issues 
from the interior of the earth is allowed to pass 
through cold water in the lagoons of Castel Nuova 
and Cherchiago ; in this way the boracic acid is 
gradually ^accumulated, till at last it may be ob- 
tained in crystals by the evaporation of the water. 
It is evident, from the temperature of the steam, that 
it must have come out of depths in which human 
beings and animals never could have lived, and yet 
it is very remarkable and highly important that am- 
monia is never absent from it. In the large works 
in Liverpool, where natural boracic acid is con- 
verted into borax, many hundred pounds of sulphate 
of ammonia are obtained at the same time. 

This ammonia has not been produced by the ani- 
mal orgafiis?n, it existed before the creation of human 
beings ; it is a part, a primary constituent, of the 
globe itself* 

The experiments instituted under Lavoisier's guid- 
ance by the Direction des Poudres et Saltpetres, have 
proved that during the evaporation of the saltpetre 
ley, the salt volatilizes with the water, and causes 
a loss which could not before be explained. It is 
known also, that in sea-storms, leaves of plants in 
the direction of the wind are covered with crystals 
of salt, even at the distance of from 20 to 30 miles 
from the sea.f But it does not require a storm to 
cause the volatilization of the salt, for the air hang- 
ing over the sea always contains enough of this sub- 
stance to make a solution of nitrate of silver turbid, 

* See extract from Professor Daubeny's Lectures, in Appendix, 
t This was observed in the United States after the great storm of 
September 23, 1815. See Professor Farrar's account in Mem. A. A. S. 



124 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

and every breeze must carry this away. Now, as 
thousands of tons of sea-water annually evaporate 
into the atmosphere, a corresponding quantity of the 
salts dissolved in it, viz. of common salt, chloride 
of potassium, magnesia, »nd the remaining constitu- 
ents of the sea-water, will be conveyed by wind to 
the land. 

This volatilization is a source of considerable loss 
in salt-works, especially where the proportion of 
salt in the water is not large. This has been com- 
pletely proved at the salt-works of Nauheim, by the 
very intelligent director of that establishment, M. - 
Wilhelmi. He hung a plate of glass between two 
evaporating houses, which were about 1200 paces 
distant from each other, and found in the morning, 
after the drying of the dew, that the glass was 
covered with crystals of salt on one or the other 
side, according to the direction of the wind. 

By the continual evaporation of the sea, its salts * 
are spread over the whole surface of the earth ; and 
being subsequently carried down by the rain, furnish 

* Analyses of sea-water. 

Of the British Channel. Of the Mediterranean. 

— Schweitzer. — Laurens. 

In 1000 parts. — Marcet. Grs. Grs. 

Water 964.74372 959.26 

Chloride of Sodium 26.660 27.05948 27.22 

" of Potassium 1.232 0.76552 O.Ol 

" of Magnesium 5.152 3.66658 6.14 

Bromide of Do 0.02929 

Sulphate of Soda 4.660 

" of Lime 1.5 1.40662 0.15 

" of Magnesia 2.29578 7.02 

Carbonate of Lime 0.03301 i ^'''^- '^™^ ^°^ \ 0.20 

^ magnesia. J 

According to M'Clemm, the water of the North Sea contains in 1000 

parts, 

24.84 Chloride of Sodium. 

2.42 Chloride of Magnesium. 

2.06 Sulpliate of Magnesia. 

1..35 Chloride of Potassium. 

1.20 Sulphate of Lime. 
In addition to these constituents, it also contains inappreciable quan- 
tities of carbonate of lime, magnesia, iron, manganese, phosphate of 
lime, iodides and bromides, silica, sulpliuretted hydrogen, and organic 
matter, together with ammonia and carbonic acid. (Liebig's Annalen 
der Chemie, Bd. xxxvii. s. 3.) 



CARBONIC ACID CONTAINED IN SEA-WATER. 125 

to the vegetation those salts necessary to its ex- 
istence. This is the origin of the salts found in the 
ashes of plants, in those cases where the soil could 
not have yielded them. 

In a comprehensive view of the phenomena of 
nature, we have no scale for that which we are 
accustomed to name, small or great ; all our ideas 
are proportioned to what we see around us, but how 
insignificant are they in comparison with the whole 
mass of the globe ! that which is scarcely observable 
in a confined district appears inconceivably large 
when reo;arded in its extension throuph unlimited 
space. The atmosphere contains only a thousandth 
part of its w^eight of carbonic acid ; and yet small 
as this proportion appears, it is quite sufficient to 
supply the whole of the present generation of living 
beings with carbon for a thousand years, even if it 
were not renew^ed. Sea-water contains j^loo of its 
weight of carbonate of lime; and this quantity, 
although scarcely appreciable in a pound, is the 
source from which myriads of marine mollusca and 
corals are supplied with materials for their habita- 
tions. 

Whilst the air contains only from 4 to 6 ten-thou- 
sandth parts of its volume of carbonic acid, sea- 
water contains 100 times more, (10,000 volumes of 
sea-water contain 620 volumes of carbonic acid — 
Laurent, Bouillon, Lagrange). Ammonia* is also 
found in this water, so that the same conditions 
which sustain livino- beinors on the land are combined 
in this medium, in which a whole world of other 
plants and animals exists. 

The roots of plants are constantly engaged in 
collecting from the rain those alkalies which formed 
part of the sea-water, and also those of the water 
of springs, which penetrates the soil. Without 
alkalies and alkaline bases most plants could not 

* When the solid saline residue obtained by the evaporation of sea- 
water is heated in a retort to redness, a sublimate of sal-ammoniac is 
obtained. — Marcet. 

11* 



126 THE ART OF CULTURE. 

exist, and without plants the alkalies would disap- 
pear gradually from the surface of the earth. 

When it is considered, that sea-water contains 
less than one-millionth of its own weight of iodine,* 
and that all combinations of iodine with the metallic 
bases of alkalies are highly soluble in water, some 
provision must necessarily be supposed to exist in 
the organization of sea-weed and the different kinds 
of Fuci, by which they are enabled during their life 
to extract iodine in the form of a soluble salt from 
sea-water, and to assimilate it in such a manner, that 
it is not again restored to the surrounding medium. 
These plants are collectors of iodine, just as land- 
plants are of alkalies ; and they yield us this ele- 
ment, in quantities such as we could not otherwise 
obtain from the water without the evaporation of 
whole seas. 

We take it for granted, that the sea-plants require 
metallic iodides f for their growth, and that their 
existence is dependent on the presence of those 
substances. With equal justice, then, we conclude, 
that the alkalies and alkaline earths, always found 
in the ashes of land-plants, are likewise necessary 
for their development. 



CHAPTER VII. 

THE ART OF CULTURE. 

The conditions necessary for the life of all vege- 
tables have been considered in the preceding part 

* This substance was discovered in 1812, and is obtained from marine 
plants; it is found also in sea- water and several mineral springs in 
combination with hydrogen, as hydriodic acid. With bases this acid 
forms hydriodates. Iodine has not been decomposed. It is a solid, 
and at about 350° F. passes into vapor of a beautiful violet color ; hence 
its name. 

t Compounds of metals and iodine. 



USE OF HUMUS. 127 

of the work. Carbonic acid, ammonia, and water 
yield elements for all the organs of plants. Certain 
inorganic substances — salts and metallic oxides — 
serve peculiar functions in their organism, and many 
of them must be viewed as essential constituents of 
particular parts. 

The atmosphere and the soil offer the same kind 
of nourishment to the leaves and roots. The former 
contains a comparatively inexhaustible supply of 
carbonic acid and ammonia; the latter, by means of 
its humus, generates constantly fresh carbonic acid, 
whilst, during the winter, rain and snow introduce 
into the soil a quantity of ammonia, sufficient for the 
development of the leaves and blossoms. 

The complete, or it may be said, the absolute 
insolubility in cold water of vegetable matter in 
progress of decay, (humus,) appears on closer con- 
sideration to be a most wise arrangement of nature. 
For if humus possessed even a smaller degree of 
solubility than that ascribed to the substance called 
humic acid, it must be dissolved by rain-water. 
Thus, the yearly irrigation of meadows, which lasts 
for several weeks, would remove a great part of it 
from the ground, and a heavy and continued rain 
would impoverish a soil. But it is soluble only when 
combined with oxygen; it can be taken up by water, 
therefore, only as carbonic acid. 

When kept in a dry place, humus may be preserved 
for centuries ; but when moistened with water, it 
converts the surrounding oxygen into carbonic acid. 
As soon as the action of the air ceases, that is, as 
soon as it is deprived of oxygen, the humus suffers 
no further change. Its decay proceeds only when 
plants grow in the soil containing it ; for they ab- 
sorb by their roots the carbonic acid as it is formed. 
The soil receives again from living plants the car- 
bonaceous matter it thus loses, so that the proportion 
of humus in it does not decrease. 

The stalactitic caverns in Franconia, and those in 
the vicinity of Baireuth, and Streitberg, lie beneath 



128 THE ART OF CULTURE. 

a fertile arable soil ; the abundant decaying vege- 
tables or humus in this soil, being acted on by 
moisture and air, constantly evolve carbonic acid, 
which is dissolved by the rain. The rain-water thus 
impregnated permeates the porous limestone, which 
forms the walls and roofs of the caverns, and dis- 
solves in its passage as much carbonate of lime as 
corresponds to the quantity of carbonic acid con- 
tained in it. Water and the excess of carbonic 
acid evaporate from this solution when it has reached 
the interior of the caverns, and the limestone is 
deposited on the walls and roofs in crystalline crusts 
of various forms. There are few spots on the earth 
where so many circumstances favorable to the pro- 
duction of humate of lime are combined, if the 
humus actually existed in the soil in the form of 
humic acid. Decaying vegetable matter, water, and 
lime in solution, are brought together, but the sta- 
lactites formed contain no trace of vegetable matter, 
and no humic acid ; they are of a glistening white 
or yellowish color, and in part transparent, like cal- 
careous spar, and may be heated to redness without 
becoming black. 

The subterranean vaults in the old castles near 
the Rhine, the " Bergstrass," and Wetherau, are 
constructed of sandstone, granite, or basalt, and 
present appearances similar to the limestone caverns. 
The roofs of these vaults or cellars are covered 
externally to the thickness of several feet with 
vegetable mould, which has been formed by the 
decay of plants. The rain falling upon them sinks 
through the earth, and dissolves the mortar by means 
of the carbonic acid derived from the mould ; and 
this solution evaporating in the interior of the vaults, 
covers them with small thin stalactites, which are 
quite free from humic acid. 

In such a filtering apparatus, built by the hand of 
nature, we have placed before us experiments which 
have been continued for a hundred or a thousand 
years. Now, if water possessed the power of dis- 



INSOLUBILITY OF HUMUS. 129 

solving a hundred-thousandth part of its own weight 
of humic acid or humate of lime, and huniic acid 
were present, we should find the inner surface of the 
roofs of these vaults and caverns covered with these 
substances ; but we cannot detect the smallest trace 
of them. There could scarcely be found a more 
clear and convincing proof of the absence of the 
humic acid of chemists in common vegetable mould. 

The common view, which has been adopted re- 
specting the modus operatidi of humic acid, does 
not afford any explanation of the following phenom- 
enon : — A very small quantity of humic acid dis- 
solved in water gives it a yellow or brown color. 
Hence it would be supposed that a soil would be 
more fruitful in proportion as it was capable of giv- 
ing this color to water, that is, of yielding it humic 
acid. But it is very remarkable that plants do not 
thrive in such a soil, and that all manure must have 
lost this property before it can exercise a favorable 
influence upon their vegetation. Water from barren 
peat soils and marshy meadows, upon which few 
plants flourish, contains much of this humic acid ; but 
all agriculturists and gardeners agree that the most 
suitable and best manure for plants is that which 
has completely lost the property of giving a color 
to water. 

The soluble substance, which gives to water a 
brown color, is a product of the putrefaction of all 
animal and vegetable matters ; its formation is an 
evidence that there is not oxygen sufficient to begin, 
or at least to complete the decay. The brown 
solutions containing this substance are decolorized 
in the air by absorbing oxygen, and a black coaly 
matter precipitates — the substance named "coal of 
humus." Now if a soil were impregnated with this 
matter, the efl"ect on the roots of plants w^ould be 
the same as that of entirely depriving the soil of 
oxygen ; plants would be as little able to grow in 
such ground as they would if hydrated protoxide 
of iron were mixed with the soil. Indeed, some 



130 THE ART OF CULTUEE. 

barren soils have been found to owe their sterility 
to this very cause. The sulphate of protoxide of 
iron (copperas), which forms a constituent of these 
soils, possesses a powerful affinity for oxygen, and 
consequently prevents the absorption of that gas by 
the roots of plants in its vicinity.* All plants die 
in soils and water which contain no oxygen; absence 
of air acts exactly in the same manner as an excess 
of carbonic acid. Stagnant water on a marshy soil 
excludes air, but a renewal of water has the same 
effect as a renewal of air, because water contains it 
in solution. If the water is withdrawn from a marsh, 
free access is given to the air, and the marsh is 
changed into a fruitful meadow. 

In a soil to which the air has no access, or at most 
but very little, the remains of animals and vegeta- 
bles do not decay, for they can only do so when 
freely supplied with oxygen; but they undergo putre- 
faction, for which air is present in sufficient quan- 
tity. Putrefaction is known to be a most powerful 
deoxidizing process, the influence of which extends 
to all surrounding bodies, even to the roots and the 
plants themselves. All substances from which oxy- 
gen can be extracted yield it to putrefying bodies ; 
yellow oxide of iron passes into the state of black 
oxide, sulphate of iron into sulphuret of iron, &c. 

The frequent renewal of air by ploughing, and the 
preparation of the soil, especially its contact with 
alkaline metallic oxides, the ashes of brown coal, 
burnt lime or limestone, change the putrefaction of 
its organic constituents into a pure process of oxi- 
dation ; and from the moment at which all the or- 
ganic matter existing in a soil enters into a state 
of oxidation or decay, its fertility is increased. The 
oxygen is no longer employed for the conversion of 

* The most obvious method of removing this salt from soils in which 
it may be contained is to manure the land with lime. The lime unites 
with the sulphuric acid and liberates the protoxide of iron, which ab- 
sorbs oxyoren with much rapidity, and is converted into the peroxide 
of iron. This conversion is accelerated by giving free access to the 
air, that is, by loosening the soil. 



INSOLUBILITY OF HUMUS. 131 

the brown soluble matter into the insoluble coal of 
humus, but serves for the formation of carbonic 
acid. This change takes place very slowly, and in 
some instances the oxygen is completely excluded 
by it ; and whenever this happens, the soil loses its 
fertility. Thus, in the vicinity of Salzhausen (a 
village in Hesse Darmstadt, famed for its mineral 
springs,) upon a meadow called Griinschwalheimer, 
unfruitful spots are seen here and there covered with 
a yellow grass. If a hole be bored from twenty to 
twenty-five feet deep in one of these spots, carbonic 
acid is emitted from it with such violence that the 
noise made by the escape of the gas may be dis- 
tinctly heard at the distance of several feet. Here 
the carbonic acid rising to the surface displaces 
completely all the air, and consequently all the oxy- 
gen, from the soil ; and without oxygen neither seeds 
nor roots can be developed; a plant will not vege- 
tate in pure nitrogen or carbonic acid gas.* 

Humus supplies young plants with nourishment 
by the roots, until their leaves are matured sufficient- 
ly to act as exterior organs of nutrition ; its quan- 
tity heightens the fertility of a soil by yielding more 
nourishment in this first period of growth, and con- 
sequently by increasing the number of organs of 
atmospheric nutrition. Those plants which receive 
their first food from the substance of their seeds, 
such as bulbous plants, could completely dispense 
with humus ; its presence is useful only in so far as 
it increases and accelerates their development, but it 
is not necessary, — indeed, an excess of it at the 
commencement of their growth is in a certain mea- 
sure injurious. 

The amount of food which young plants can take 
from the atmosphere in the form of carbonic acid 
and ammonia is limited; they cannot assimilate more 
than the air contains. Now, if the quantity of their 
stems, leaves, and branches has been increased by 

* See note p. 79. 



132 THE ART OF CULTURE. 

the excess of food yielded by the soil at the com- 
mencement of their development, they will require 
for the completion of their growth, and for the for- 
mation of their blossoms and fruits, more nourish- 
ment from the air than it can afford, and consequently 
they will not reach maturity. In many cases the 
nourishment afforded by the air under these circum- 
stances suffices only to complete the formation of 
the leaves, stems, and branches. The same result 
then ensues as when ornamental plants are trans- 
planted from the pots in which they have grown to 
larger ones, in which their roots are permitted to 
increase and multiply. All their nourishment is em- 
ployed for the increase of their roots and leaves; 
they spring, as it is said, into an herb or weed, but 
do not blossom. When, on the contrary, we take 
away part of the branches, and of course their leaves 
with them, from dwarf trees, since we thus prevent 
the development of new branches, an excess of 
nutriment is artificially procured for the trees, and 
is employed by them in the increase of the blossoms 
and enlaro-ement of the fruit. It is to effect this 

o 

purpose that vines are pruned. 

A new and peculiar process of vegetation ensues 
in all perennial plants, such as shrubs, fruit and 
forest trees, after the complete maturity of their 
fruit. The stem of annual plants at this period of 
their growth becomes woody, and their leaves change 
in color. The leaves of trees and shrubs, on the 
contrary, remain in activity until the commencement 
of the winter. The formation of the layers of wood 
progresses, the wood becomes harder and more solid, 
but after August the leaves form no more wood ; all 
the carbonic acid which the plants now absorb is 
employed for the production of nutritive matter for 
the following year : instead of woody fibre, starch is 
formed, and is diffused through every part of the 
plant by the autumnal sap (seve d'Aout).* Ac- 

* Hartig, in Erdmann und Schweigger-Seidels Journal, V. 217. 1S35. 



EXCESS OF NUTRIMENT. 133 

cording to the observations of M. Heyer, the starch 
thus deposited in the body of the tree can be recog- 
nised in its known form by the aid of a good micro- 
scope. The barks of several aspens and pine-trees * 
contain so much of this substance, that it can be 
extracted from them as from potatoes by trituration 
with water. It exists also in the roots and other 
parts of perennial plants. A very early winter, or 
sudden change of temperature, prevents the forma- 
tion of this provision for the following year; the 
wood, as in the case of the vine-stock, does not 
ripen, and its growth is in the next year very 
limited. 

From the starch thus accumulated, sugar and gum 
are produced in the succeeding spring, while from 
the gum those constituents of the leaves and young 
sprouts "which contain no nitrogen are in their turn 
formed. After potatoes have germinated, the quantity 
of starch in them is found diminished. The juice of 
the maple-tree ceases to be sweet from the loss of its 
sugar when its buds, blossoms, and leaves attain 
their maturity. 

The branch of a willow, which contains a large 
quantity of granules of starch in every part of its 
woody substance, puts forth both roots and leaves 
in pure distilled rain-water; but in proportion as it 

* It is well known that bread is made from the bark of pines in 
Sweden during famines. 

The fallowing directions are given by Professor Aiitenrieth for pre- 
parino; a palatable and nutritious bread from the heech and other woods 
destitute of turpentine. Every thing soluble in water is first removed 
by frequent maceration and boiling, Ihe wood is then to be reduced to 
a minute state of division, not merely into fine fibres, but actual pow- 
der ; and after being repeatedly subjected to heat in an oven, is ground 
in the usual manner of corn. Wood thus prepared, according to the 
author, acquires the smell and tiisle of corn flour. It is, however, 
never quite white. It agrees with corn flour in not fermenting with- 
out the addition of leaven, and in this case some leaven of corn flour is 
found to answer best. With this it makes a perfectly uniform and 
spongy bread ; and when it is thoroughly baked, and has much crust, 
it lias a much better taste of bread than what in time of scarcity is pre- 
pared from the bran and husks of corn. Wood-flour also, boiled in 
water, forms a thick, tough, trembling jelly, which is very nutritious. 

Pkilosopldcal Transactions. 18:27. 

12 



134 THE ART OF CULTURE. 

grows, the starch disappears, it being evidently ex- 
hausted for the formation of the roots and leaves. 
In the course of these experiments, M. Heyer made 
the interesting observation, that such branches when 
placed in snow-water (which contains ammonia) 
produced roots three or four times longer than those 
which they formed in pure distilled water, and that 
this pure water remained clear, while the rain-water 
gradually acquired a yellow color. 

Upon the blossoming of the sugar-cane, likewise, 
part of the sugar disappears; and it has been ascer- 
tained, that the sugar does not accumulate in the 
beet-root until after the leaves are completely formed. 

Much attention has recently been drawn to the 
fact that the produce of potatoes may be much in- 
creased by plucking off the blossoms from the plants 
producing them, a result quite consistent with theo- 
ry. This important observation has been completely 
confirmed by M. Zeller, the director of the Agricul- 
tural Society at Darmstadt. In the year 1839, two 
fields of the same size, lying side by side and ma- 
nured in the same manner, were planted with pota- 
toes. When the plants had flowered, the blossoms 
were removed from those in one field, while those in 
the other field were left untouched. The former pro- 
duced 47 bolls, the latter only 37 bolls. 

These well-authenticated observations remove ev- 
ery doubt as to the part which sugar, starch, and 
gum play in the development of plants ; and it ceases 
to be enigmatical, why these three substances exer- 
cise no influence on the growth or process of nutri- 
tion of a matured plant, when supplied to them as 
food. 

The accumulation of starch in plants during the 
autumn has been compared, although certainly erro- 
neously, to the fattening of hibernating animals be- 
fore their winter sleep ; but in these animals every 
vital function, except the process of respiration, is 
suspended, and they only require, like a lamp slowly 
burning, a substance rich in carbon and hydrogen to 



EXCESS OF NUTRIMENT. 135 

support the process of combustion in the lungs. On 
their awaking from their torpor in the spring, the fat 
has disappeared, but has not served as nourishment. 
It has not caused the least increase in any part of 
their body, neither has it changed the quality of any 
of their organs. With nutrition, properly so called, 
the fat in these animals has not the least connexion. 

The annual plants form and collect their future 
nourishment in the same way as, the perennial ; they 
store it in their seeds in the form of vegetable albu- 
men, starch and gum, which are used by the germs 
for the formation of their leaves and first radicle 
fibres. The proper nutrition of the plants, their in- 
crease in size, begins after these organs are formed. 

Every germ and every bud of a perennial plant is 
the engrafted embryo of a new individual, while the 
nutriment accumulated in the stem and roots, corre- 
sponds to the albumen of the seeds. 

Nutritive matters are, correctly speaking, those 
substances which, when presented from without, are 
capable of sustaining the life and all the functions 
of an organism, by furnishing to the different parts 
of plants the materials for the production of their 
peculiar constituents. 

In animals, the blood is the source of the material 
of the muscles and nerves ; by one of its component 
parts, the blood supports the process of respiration, 
by others, the peculiar vital functions ; every part of 
the body is supplied with nourishment by it, but its 
own production is a special function, without which 
v;e could not conceive life to continue. If we destroy 
the activity of the organs which produce it, or if we 
inject the blood of one animal into the veins of an- 
other, at all events, if we carry this beyond certain 
limits, death is the consequence. 

If we could introduce into a tree woody fibre in a 
state of solution, it would be the same thing as plac- 
ing a potato plant to vegetate in a paste of starch. 
The office of the leaves is to form starch, woody fibre, 
and sugar; consequently, if we convey these sub- 



136 THE ART OF CULTURE. 

stances through the roots, the vital functions of the 
leaves must cease, and if the process of assimilation 
cannot take another form, the plant must die. 

Other substances must be present in a plant, be- 
sides the starch, sugar, and gum, if these are to take 
part in the development of the germ, leaves, and first 
radicle fibres. There is no doubt that a grain of 
wheat contains within itself the component parts of 
the germ and of the radicle fibres, and, we must sup- 
pose, exactly in the proportion necessary for their 
formation. These component parts are starch and 
gluten; and it is evident that neither of them alone, 
but that both simultaneously assist in the formation 
of the root, for they both suffer changes under the 
action of air, moisture, and a suitable temperature. 
The starch is converted into sugar, and the gluten 
also assumes a new form, and both acquire the capa- 
bility of being dissolved in water, and of thus being 
conveyed to every part of the plant. Both the starch 
and the gum are completely consumed in the forma- 
tion of the first part of the roots and leaves ; an ex- 
cess of either could not be used in the formation of 
leaves, or in any other way. 

The conversion of starch into sugar during the 
germination of grain is ascribed to a vegetable princi- 
ple called diastase, \v\iich. is generated during the act 
of commencing germination. But this mode of trans- 
formation can also be effected by gluten, although it 
requires a longer time. Seeds, which have germin- 
ated, always contain much more diastase than is 
necessary for the conversion of their starch into 
sugar, for five parts by weight of starch can be con- 
verted into sugar by one part of malted barley. 
This excess of diastase can by no means be regarded 
as accidental, for, like the starch, it aids in the form- 
ation of the first organs of the young plant, and dis- 
appears with the sugar ; diastase contains nitrogen 
and furnishes the elements of vegetable albumen. 

Carbonic acid, water, and ammonia, are the food 
of fully-developed plants j starch, sugar, and gum, 



CONDITIONS ESSENTIAL TO NUTRITION. 137 

serve, when accompanied by an azotized substance, 
to sustain the embryo, until its first organs of nutri- 
tion are unfolded. The nutrition of a foetus and de- 
velopment of an egg proceed in a totally different 
manner from that of an animal which is separated 
from its parent; the exclusion of air does not en- 
danger the life of the foetus, but would certainly 
cause the death of the independent animal. In the 
same manner, pure water is more advantageous to 
the growth of a young plant, than that containing 
carbonic acid, but after a month the reverse is the 
case. 

The formation of sugar in maple-trees does not 
take place in the roots, but in the woody substance 
of the stem. The quantity of sugar in the sap aug- 
ments until it reaches a certain height in the stem 
of the plant, above w^hich point it remains stationary. 

Just as germinating barley produces a substance 
which, in contact w4th starch, causes it to lose its 
insolubility and to become sugar, so in the roots of 
the maple, at the commencement of vegetation, a 
substance must be formed, which, being dissolved in 
Waaler, permeates the wood of the trunk, and con- 
verts into sugar the starch, or whatever it may be, 
which it finds deposited there. It is certain, that 
when a hole is bored into the trunk of a maple-tree 
just above its roots, filled with sugar, and then closed 
again, the sugar is dissolved by the ascending sap. 
It is further possible that this sugar maybe disposed 
of in the same manner as that formed in the trunks ; 
at all events it is certain, that the introduction of it 
does not prevent the action of the juice upon the 
starch, and since the quantity of the sugar present is 
now greater than can be exhausted by the leaves 
and buds, it is excreted from the surface of the 
leaves or bark. Certain diseases of trees, for exam- 
ple that called honey-dew, evidently depend on the 
want of the due proportion between the quantity of 
the azotized and that of the unazotized substances 
which are applied to them as nutriment. 
12* 



138 THE ART OF CULTURE. 

In whatever form, therefore, we supply plants with 
those substances which are the products of their 
own action, in no instance do they appear to have 
any effect upon their growth, or to replace what they 
have lost. Sugar, gum, and starch, are not food for 
plants, and the same must be said of humic acid, 
which is so closely allied to them in composition. 

If now we direct our attention to the particular 
organs of a plant, we find every fibre and every 
particle of wood surrounded by a juice containing 
an azotized matter; while the starch, granules, and 
sugar, are enclosed in cells formed of a substance 
containing nitrogen. Indeed everywhere, in all the 
juices of the fruits and blossoms, we find a substance 
destitute of nitrogen, accompanied by one which 
contains that element. 

The wood of the stem cannot be formed, quasi 
wood, in the leaves, but another substance must be 
produced which is capable of being transformed into 
wood. This substance must be in a state of solution, 
and accompanied by a compound containing nitro- 
gen ; it is very probable that the wood and the 
vegetable gluten, the starch granules and the cells 
containing them, are formed simultaneously, and in 
this case a certain fixed proportion between them 
would be a condition necessary for their production. 

According to this view, the assimilation of the 
substances generated in the leaves will (^cceteris 
paribus) depend on the quantity of nitrogen con- 
tained in the food. When a sufficient quantity of 
nitrogen is not present to aid in the assimilation of 
the substances which do not contain it, these sub- 
stances will be separated as excrements from the 
bark, roots, leaves, and branches. The exudations 
of mannite, gum, and sugar, in strong and healthy 
plants cannot be ascribed to any other cause.* 

* M. Trapp in Giessen possesses a Clcrodcndrnn fragrans, which 
grows in the house, and exudes on the surface of its leaves in Sep- 
tember large colorless drops of sugar-candy, which form regular crys- 
tals upon drying; — I am not aware whether the juice of this plant 



CONDITIONS ESSENTIAL TO NUTRITION. 139 

Analogous phenomena are presented by the pro- 
cess of digestion in the human organism. In order 
that the loss which every part of the body sustains 
by the processes of respiration and perspiration may 
be restored to it, the organs of digestion require to 
be supplied with food, consisting of substances con- 
taining nitrogen, and of others destitute of it, in 
definite proportions. If the substances which do 
not contain nitrogen preponderate, either they will 
be expended in the formation of fat, or they will 
pass unchanged through the organism. This is par- 
ticularly observed in those people who live almost 
exclusively upon potatoes ; their excremejits contain 
a large quantity of unchanged granules of starch, 
of which no trace can be detected when gluten or 
flesh is taken in proper proportions, because in this 
case the starch has been rendered capable of assim- 
ilation. Potatoes, which when mixed with hay alone 
are scarcely capable of supporting the strength of a 
horse, form with bread and oats a strong and whole- 
some fodder. 

It will be evident from the preceding considera- 
tions, that the products generated by a plant may 
vary exceedingly, according to the substances given 
it as food. A superabundance of carbon in the state 
of carbonic acid conveyed through the roots of 
plants, without being accompanied by nitrogen, can- 
not be converted either into gluten, albumen, wood, 
or any other component part of an organ; but either 
it will be separated in the form of excrements, such 
as sugar, starch, oil, wax, resin, mannite,* or gum, 
or these substances will be deposited in greater or 
less quantity in the wide cells and vessels. 

contains sugar. Professor Redtenbacher, of Prague, informs me that 
he has analyzed the crystals, and found them to be perfectly pure 
sugar. — Ed. 

* Mannite forms the greater part of manna. It is found in the 
juices of several fruits, in the fermented juice of beet-root, carrots, 
onions, &c. ; it is also obtained in small quantity when starch is 
transformed into grape sugar by boiling with dilute sulphuric acid. 
It crystallizes in prisms, is faintly sweet, soluble in water and hot 
alcohol. Its aqueous solution cannot be made to undergo the vinous 
fermentation. Its formula is Ce H? Og. 



140 THE ART OF CULTURE. 

The quantity of gluten, vegetable albumen, and 
mucilage, will augment when plants are supplied 
with an excess of food containing nitrogen; and 
ammoniacal salts will remain in the sap, when, for 
example, in the culture of the beet, we manure the 
soil with a highly nitrogenous substance, or when 
we suppress the functions of the leaves by removing 
them from the plant. 

We know that the ananas is scarcely eatable in 
its wild state, and that it shoots forth a great quan- 
tity of leaves when treated with rich animal manure, 
without the fruit on that account acquiring a large 
amount of sugar ; that the quantity of starch in 
potatoes increases when the soil contains much 
humus, but decreases when the soil is manured with 
strong animal manure, although then the number -of 
cells increases, the potatoes acquiring in the first 
case a mealy, in the second a soapy, consistence. 
Beet-roots taken from a barren, sandy soil contain 
a maximum of sugar, and no ammoniacal salts; and 
the Teltowa parsnep loses its mealy state in a 
manured land, because there all the circumstances 
necessary for the formation of cells are united.* 

An abnormal! production of certain component 
parts of plants presupposes a power and capability 
of assimilation to which the most powerful chemical 
action cannot be compared. The best idea of it may 
be formed by considering that it surpasses in power 
the strongest galvanic battery, wuth which we are 
not able to separate the oxygen from carbonic acid. 
The affinity of chlorine for hydrogen, and its power 
to decompose \vater under the influence of light 

* Children fed upon arrow-root, salep, or indeed any kind of amyla- 
ceous food, which does not contain ingredients fitted for the formation 
of bones and muscles, become fiit, and acquire much cmhonpoint ; their 
limbs appear full, but they do not acquire strength, nor are their organs 
properly developed. — L. 

t Abnormal, (Lat. ab, from, and norma, a rule,) Any thing without, 
or contrary to, system or rule. In botany, if a flower has five petals, 
the rule is, tliat it should have the same number of stamens, or some 
regular multiple of that number; if it has only four or six stamens, 
the flower is abnormal. 



EFFECT OF LIGHT ON CHEMICAL COMBINATION. 141 

and set at liberty its oxygen, cannot be considered 
as at all equalling the power and energy with which 
a leaf separated from a plant decomposes the car- 
bonic acid which it absorbs. 

The common opinion, that only the direct solar 
rays can effect the decomposition of carbonic acid 
in the leaves of plants, and that reflected or diffused 
light does not possess this property, is wholly an 
error, for exactly the same constituents are generated 
in a number of plants, whether the direct rays of 
the sun fall upon them, or whether they grow in the 
shade. They require light, and indeed sunlight, 
but it is not necessary that the direct rays of the 
sun reach them. Their functions certainly proceed 
with greater intensity and rapidity in sunshine than 
in the diffused light of day ; but there is nothing 
more in this than the similar action which light 
exercises on ordinary chemical combinations ; it 
merely accelerates in a greater or less degree the 
action already subsisting. 

Thus chlorine* and hydrogen combining form muri- 
atic (hydrochloric) acid. This combination is effected 
in a few hours in common daylight, but it ensues in- 
stantly, with a violent explosion, under exposure to 
the direct solar rays, whilst not the slightest change 
in the two gases takes place in perfect darkness. 
When the liquid hydrocarburet of chlorine, resulting 
from the union of the defiant gasf of the associated 

* Chlorine is a gas named from its green color ; it was formerly 
called oxymviriatic acid. It has not been decomposed. It is one of the 
most suffocating of the gases, and highly irritating, even when much 
diluted with air. It is largely absorbed by water, and the solution has 
the property of bleaching. Its solution in water cannot be kept un- 
changed, as the chlorine unites to the hydrogen of the water and 
forms muriatic or hydrochloric acid. 

Bleaching salts are formed by exposing lime to an atmosphere of 
chlorine. Chlorine is useful for removing offensive odors. A few 
table spoonfuls of bleaching powder, sprinkled occasionally in privies, 
and in larger quantities upon heaps of offensive substances, upon the 
floors of slaughter-houses, «&c. will destroy the unpleasant odor, and 
at the same time add to the value of the manure. 

For description of chlorine, a:id the method of procuring it, see 
Webster's Chemistry, 'M edit, p 1(S0. 

t One of the compounds of hydrogen and carbon. 



142 THE ART OF CULTURE. 

Dutch chemists with chlorine, is exposed in a vessel 
with chlorine gas to the direct solar rays, chloride 
of carbon is immediately produced ; but the same 
compound can be obtained with equal facility in the 
diffused light of day, -a longer time only being re- 
quired. When this experiment is performed in the 
way first mentioned, two products only are observed 
(muriatic acid and perchloride of carbon) ; whilst by 
the latter method a class of intermediate bodies are 
produced, in which the quantity of chlorine con- 
stantly augments, until at last the whole liquid 
hydrocarburet of chlorine is converted into the same 
two products as in the first case. Here, also, not 
the slightest trace of decomposition takes place in 
the dark. Nitric acid is decomposed in common 
daylight into oxygen, and peroxide of nitrogen; and 
chloride of silver becomes black in the diffused light 
of day, as well as in the direct solar rays; — in 
short, all actions of a similar kind proceed in the 
same way in diffused light as well as in the solar 
light, the only difference consisting in the time in 
which they are effected. It cannot be otherwise in 
plants, for the mode of their nutriment is the same 
in all, and their component substances afford proof 
that their food has suffered absolutely the same 
change, whether they grow in the sunshine or in the 
shade. 

All the carbonic acid, therefore, which we supply 
to a plant will undergo a transformation, provided 
its quantity be not greater than can be decomposed 
by the leaves. We know that an excess of carbonic 
acid kills plants, but we know also that nitrogen to 
a certain degree is not essential for the decomposi- 
tion of carbonic acid. All the experiments hitherto 
instituted prove, that fresh leaves placed in water 
impregnated with carbonic acid, and exposed to the 
influence of solar light, emit oxygen gas, whilst the 
carbonic acid disappears. Now in these experiments 
no nitrogen is supplied at tlie same time with the car- 
bonic acid; hence no other conclusion can be drawn 



IMPORTAx\CE OF AGRICULTURE. 143 

from them than that nitrogen is not necessary for 
the decomposition of carbonic acid, — for the exer- 
cise, therefore, of one of the functions of plants. 
And yet the presence of a substance containing this 
element appears to be indispensable for the assimila- 
tion of the products newly formed by the decompo- 
sition of the carbonic acid, and their consequent 
adaptation for entering into the composition of the 
different organs. 

The carbon abstracted from the carbonic acid 
acquires in the leaves a new form, in which it is 
soluble and transferable to all parts of the plant. 
In this new form the carbon aids in constituting 
several new products ; these are named sugar when 
they possess a sweet taste, gum or mucilage when 
tasteless, and excrementitious matters when expelled 
by the roots. 

Hence it is evident, that the quantity and quality 
of the substances generated by the vital processes of 
a plant will vary according to the proportion of the 
different kinds of food with which it is supplied. 
The development of every part of a plant in a free 
and uncultivated state depends on the amount and 
nature of the food afforded to it by the spot on 
which it grows. A plant is developed on the most 
sterile and unfruitful soil as well as on the most 
luxuriant and fertile, the only difference which can 
be observed being in its height and size, in the num- 
ber of its twigs, branches, leaves, blossoms, and 
fruit. Whilst the individual organs of a plant in- 
crease on a fertile soil, they diminish on another 
where those substances which are necessary for their 
formation are not so bountifully supplied ; and the 
proportion of the constituents which contain nitrogen 
and of those which do not in plants varies with the 
amount of nitrogenous matters in their food. 

The development of the stem, leaves, blossoms, 
and fruit of plants is dependent on certain con- 
ditions, the knowledge of which enables us to ex- 
ercise some influence on their internal constituents 



144 THE ART OF CULTURE. 

as well as on their size. It is the duty of the natu- 
ral philosopher to discover what these conditions 
are ; for the fundamental principles of agriculture 
must be based on a knowledge of them. There is 
no profession which can be compared in importance 
wnth that of agriculture, for to it belongs the pro- 
duction of food for man and animals ; on it depends 
the welfare and development of the whole human 
species, the riches of states, and all commerce. 
There is no other profession in which the applica- 
tion of correct principles is productive of more bene- 
ficial effects, or is of greater and more decided in- 
fluence. Hence it appears quite unaccountable, that 
we may vainly search for one leading principle in the 
writings of agriculturists and vegetable physi^ologists. 

The methods employed in the cultivation of land 
are different in every country, and in every district ; 
and when we inquire the causes of these differences, 
we receive the answer, that they depend upon cir- 
cumstances. {^Les circonstances font les assolements.^ 
No answer could show ignorance more plainly, since 
no one has ever yet devoted himself to ascertain 
what these circumstances are. Thus also when we 
inquire in what manner manure acts, we are answered 
by the most intelligent men, that its action is covered 
by the veil of Isis ; and when we demand further 
what this means, we discover merely that the excre- 
ments of men and animals are supposed to contain 
an incomprehensible something which assists in the 
nutrition of plants, and increases their size. This 
opinion is embraced without even an attempt being 
made to discover the component parts of manure, 
or to become acquainted with its nature.* 

In addition to the general conditions, such as heat, 
light, moisture, and the component parts of the atmo- 
sphere, which are necessary for the growth of all 
plants, certain substances are found to exercise a 

* This statement is now somewhat too general ; both in this country 
and in Great Britain airriculture has received important aid from the 
labors of chemists and physiologists. 



OBJECT OF AGRICULTURE. 145 

peculiar influence on the development of particular 
families. These substances either are already con- 
tained in the soil, or are supplied to it in the form 
of the matters known under the general name of 
manure. But what does the soil contain, and what 
are the components of the substances used as ma- 
nure ? Until these points are satisfactorily deter- 
mined, a rational system of agriculture cannot exist. 
The power and knowledge of the physiologist, of the 
agriculturist and chemist, must be united for the 
complete solution of these questions ; and in order 
to attain this end, a commencement must be made. 

The general object of agriculture is to produce in 
the most advantageous manner certain qualities, or 
a maximum size, in certain parts or organs of par- 
ticular plants. Now, this object can be attained 
only by the application of those substances which 
we know to be indispensable to the development of 
these parts or organs, or by supplying the conditions 
necessary to the production of the qualities desired. 

The rules of a rational system of agriculture should 
enable us, therefore, to give to each plant that 
which it requires for the attainment of the object in 
view. 

The special object of agriculture is to obtain an 
abnormal development and production of certain 
parts of plants, or of certain vegetable matters, 
which are employed as food for man and animals, or 
for the purpose of industry. 

The means employed for effecting these two pur- 
poses are very different. Thus the mode of culture, 
employed for the purpose of procuring fine pliable 
straw for Florentine hats, is the very opposite to 
that which must be adopted in order to produce a 
maximum of corn from the same plant. Peculiar 
methods must be used for the production of nitrogen 
in the seeds, others for giving strength and solidity 
to the straw, and others again must be followed 
when w^e wish to give such strength and solidity to 
13 



146 THE ART OF CULTURE. 

the straw as will enable it to bear the weight of the 
ears. 

We must proceed in the culture of plants in pre- 
cisely the same manner as we do in the fattening 
of animals. The flesh of the stag and roe, or of 
wild animals in general, is quite devoid of fat, like 
the muscular flesh of the Arab; or it contains only 
small quantities of it. The production of flesh and 
fat may be artificially increased; all domestic ani- 
mals, for example, contain much fat. We give food 
to animals, which increases the activity of certain 
organs, and is itself capable of being transformed 
into fat. We add to the quantity of food or we 
lessen the processes of respiration and perspiration 
by preventing motion. The conditions necessary to 
effect this purpose in birds are different from those 
in quadrupeds ; and it is well known that charcoal 
powder produces such an excessive growth of the 
liver of a goose, as at length causes the death of the 
animal. 

The increase or diminution of the vital activity of 
vegetables depends only on heat and solar light, 
which we have not arbitrarily at our disposal : all 
that we can do is to supply those substances which are 
adapted for assimilation by the power already present 
in the organs of the plant. But what then are these 
substances ? They may easily be detected by the ex- 
amination of a soil, which is always fertile in given 
cosmical and atmospheric conditions ; for it is evi- 
dent, that the knowledge of its state and compo- 
sition must enable us to discover the circumstances 
under which a sterile soil may be rendered fertile. 
It is the duty of the chemist to explain the com- 
position of a fertile soil, but the discovery of its 
proper state or condition belongs to the agricul- 
turist ; our present business lies only with the former. 

Arable land is originally formed by the crumbling 
of rocks, and its properties depend on the nature 
of their principal component parts. Sand, clay, and 



FERTILITY OF DIFFERENT SOILS- 147 

lime, are the names given to the principal constitu- 
ents of the different kinds of soil. 

Pure sand and pure limestones, in which there are 
no other inorganic substances except siliceous earth, 
carbonate or silicate of lime, form absolutely barren 
soils. But argillaceous earths form always a part 
of fertile soils. Now from whence come the argil- 
laceous earths in arable land, what are their con- 
stituents, and what part do they play in favoring 
vegetation ? They are produced by the disintegra- 
tion of aluminous minerals by the action of the 
weather; the common potash and soda felspars, 
Labrador spar, mica, and the zeolites, are the most 
common aluminous earths, which undergo this change. 
These minerals are found mixed with other sub- 
tances in granite, gneiss, mica-slate, porphyry, clay- 
slate, grauwacke, and the volcanic rocks, basalt, clink- 
stone, and lava. In the grauwacke, we have pure 
quartz, clay-slate, and lime ; in the sandstones, quartz 
and loam. The transition limestone and the dolo- 
mites contain an intermixture of clay, felspar, por- 
phyry, and clay-slate ; and the mountain limestone 
is remarkable for the quantity of argillaceous earths 
which it contains. Jura limestone contains 3 — 20, 
that of the Wurtemberg Alps 45 — 50 per cent, of 
these earths. And in the miischelkalk and the cal- 
caire grassier they exist in greater or less quantity. 

It is known, that the aluminous minerals are the 
most widely diffused on the surface of the earth, and 
as we have already mentioned, all fertile soils, or 
soils capable of culture, contain alumina as an inva- 
riable constituent. There must, therefore, be some- 
thing in aluminous earth which enables it to exercise 
an influence on the life of plants, and to assist in 
their development. The property on which this de- 
pends is that of its invariably containing potash and 
soda. 

Alumina exercises only an indirect influence on 
vegetation, by its power of attracting and retaining 
water and ammonia ; it is itself very rarely found in 



148 THE ART OF CULTURE. 

the ashes of plants,* but silica is always present, 
having in most places entered the plants by means 
of alkalies. In order to form a distinct conception 
of the quantities of alkalies in aluminous minerals, it 
must be remembered that felspar contains 17| per 
cent, of potash, albite ir43 per cent, of- soda, and 
mica 3 — 5 percent.; and that zeolite contains 13 

— 16 per cent, of both alkalies taken together. The 
late analyses of Ch, Graelin, Lowe, Fricke, Meyer, 
and Redtenbacher, have also shown, that basalt con- 
tains from I to 3 per cent, of potash, and from 5 — 7 
per cent, of soda, that clay-slate contains from 2-75 

— 3-31 per cent, of potash, and loam from 1| — 4 
per cent, of potash. 

If, now, we calculate from these data, and from 
the specific weights of the different substances, how 
much potash must be contained in a layer of soil, 
which has been formed by the disintegration of 
26,910 square feet (1 Hessian acre) of one of these 
rocks to the depth of 20 inches, we find that a soil of 

Felspar containf? 1,269,000 lbs. 

Clink-stone " from 220,400 to 440,000 " 
Basalt " " 52,300 " 82,600 " 

Clay-slate " " 110,0(i0 " 220,400 " 

Loam " " 95,800 " 330,600 " 

Potash is present in all clays ; according to Fuchs, 
it is contained even in marl; it has been found in all 
the argillaceous earths in which it has been sought. 
The fact that they contain potash may be proved in 
the clays of the transition and stratified mountains, 
as well as in the recent formations surrounding Ber- 
lin, by simply digesting them with sulphuric acid, by 
which process alum is formed. (Mitscherlich.) It 
is well known also to all manufacturers of alum, that 
the leys contain a certain quantity of this salt ready 

* Alumina is generally supposed to be a common ingredient of the 
ashes of plants, and it is very frequently stated in the results of their 
analyses ; but in most cases it has been mistaken for phospliate of mag- 
nesia, or phosphate of alumina, with which it has many properties in 
common, and from which it cannot be distinguished without much care 
and attention. — Ed. 



FERTILITY OF DIFFERENT SOILS. 149 

formed, the potash of which has its origin from the 
ashes of the stone and brown coal, which contain 
much argillaceous earth. 

When we consider this extraordinary distribution 
of potash over the surface of the earth, is it reason- 
able to have recourse to the idea, that the presence 
of this alkali in plants is due to the generation of a 
metallic oxide by a peculiar organic process from the 
component parts of the atmosphere 1 This opinion 
found adherents even after the method of detecting 
potash in soils was known, and suppositions of the 
same kind may be found even in the writings of some 
physiologists of the present day. Such opinions be- 
long properly to the time when flint was conceived 
to be a product of chalk, and when everything which 
appeared incomprehensible on account of not having 
been investigated, was explained by assumptions far 
more incomprehensible. 

A thousandth part of loam mixed with the quartz 
in new red sandstone, or with the lime in the differ- 
ent limestone formations, affords as much potash to 
a soil only twenty inches in depth as is sufficient to 
supply a forest of pines growing upon it for a centu- 
ry. A single cubic foot of felspar is sufficient to 
supply a wood, covering a surface of 26,910 square 
feet, with the potash required for five years. 

Land of the greatest fertility contains argillaceous 
earths and other disintegrated minerals with chalk 
and sand in such a proportion as to give free access 
to air and moisture. The land in the vicinity of 
Vesuvius may be considered as the type of a fertile 
soil, and its fertility is greater or less in different 
parts, according to the proportion of clay or sand 
which it contains. 

The soil which is formed by the disintegration of 
lava cannot possibly, on account of its origin, con- 
tain the smallest trace of vegetable matter, and yet 
it is well known that when the volcanic ashes have 
been exposed for some time to the influence of air 
and moisture, a soil is gradually formed in which all 
13* 



150 THE ART OF CULTURE. 

kinds of plants grow with the greatest luxuriance 
This fertility is owing to the alkalies which are con- 
tained in the lava, and which by exposure to the 
weather are rendered capable of being absorbed by 
plants. Thousands of years have been necessary to 
convert stones and rocks into the soil of arable land, 
and thousands of years more will be requisite for 
their perfect reduction, that is, for the complete ex- 
haustion of their alkalies. 

We see from the composition of the water in riv- 
ers, streamlets, and springs, how little rain-water is 
able to extract alkali from a soil, even after a term 
of years ; this water is generally soft, and the com- 
mon salt, which even the softest invariably contains, 
proves, that those alkaline salts, which are carried 
to the sea b}"^ rivers and streams, are returned again 
to the land by wind and rain. 

Nature itself shows us what plants require at the 
commencement of the development of their germs 
and first radicle fibres. Becquerel has shown, that 
the gramitiecB, leguminosce, cruciferce, cichoracecc, um- 
helliferce^ coniferiB, and cucurhitacefB emit acetic acid 
during germination. A plant which has just broken 
through the soil, and a leaf just burst open from the 
bud, furnish ashes by incineration, which contain as 
nauch, and generally more, of alkaline salts than at 
any period of their life. (De Saussure.) Now we 
know also, from the experiments of Becquerel, in \Yhat 
manner these alkaline salts enter young plants ; the 
acetic acid formed during germination is diffused 
through the wet or moist soil, becomes saturated 
with lime, magnesia, and alkalies, and is again ab- 
sorbed by the radicle fibres in the form of neutral 
salts. After the cessation of life, when plants are 
subjected to decomposition by means of decay and 
putrefaction, the soil receives again that which had 
been extracted from it. 

Let us suppose, that a soil has been formed by the 
action of the weather on the component parts of 
granite, grauwacke, mountain limestone, or porphy- 



DISINTEGRATION OF SOILS. 151 

ry, and that nothing has vegetated on it for thou- 
sands of years. Now this soil would become a mag- 
azine of alkalies in a condition favorable for their 
assimilation by the roots of plants. 

The interesting experiments of Striive have proved 
that water impregnated with carbonic acid decom- 
poses rocks which contain alkalies, and then dis- 
solves a part of the alkaline carbonates. It is evi- 
dent that plants also, by producing carbonic acid 
during their decay, and by means of the acids which 
exude from their roots in the living state, contribute 
no less powerfully to destroy the coherence of rocks. 
Next to the action of air, water, and change of tem- 
perature, plants themselves are the most powerful 
agents in effecting the disintegration of rocks. 

Air, water, and the change of temperature prepare 
the different species of rocks for yielding to plants 
the alkalies which they contain. A soil which has 
been exposed for centuries to all the influences which 
affect the disintegration of rocks, but from which the 
alkalies have not been removed, will be able to afford 
the means of nourishment to those vegetables which 
require alkalies for their growth during many years ; 
but it must gradually become exhausted, unless those 
alkalies which have been removed are again replaced ; 
a period, therefore, will arrive when it will be neces- 
sary to expose it from time to time to a further dis- 
integration, in order to obtain a new supply of solu- 
ble alkalies. For small as is the quantity of alkali 
which plants require, it is nevertheless quite indis- 
pensable for their perfect development. But when 
one or more years have elapsed without any alkalies 
having been extracted from the soil, a new harvest 
may be expected. 

The first colonists of Virginia found a country the 
soil of which was similar to that mentioned above ; 
harvests of wheat and tobacco were obtained for a 
century from one and the same field, without the aid 
of manure ; but now whole districts are converted 
into unfruitful pasture-land, which without manure 



152 THE ART OF CULTURE. 

produces neither wheat nor tobacco. From every 
acre of this land there were removed in the space 
of one hundred years 13,200 lbs. of alkalies in 
leaves, grain, and straw ; it became unfruitful, there- 
fore, because it was deprived of every particle of 
alkali, which had been reduced to a soluble state, 
and because that which was rendered soluble again 
in the space of one year was not sufficient to satisfy 
the demands of the plants. Almost all the culti- 
vated land in Europe is in this condition; fallow is 
the term applied to land left at rest for further 
disintegration. It is the greatest possible mistake 
to suppose that the temporary diminution of fertility 
in a soil is owing to the loss of humus ; it is the 
mere consequence of the exhaustion of the alkalies. 

Let us consider the condition of the country 
around Naples, which is famed for its fruitful corn- 
land ; the farms and villages are situated from 
eighteen to twenty-four miles distant from one an- 
other, and between them there are no roads, and 
consequently no transportation of manure. Now 
corn has been cultivated on this land for thousands 
of years, without any part of that which is annually 
removed from the soil being artificially restored to 
it. How can any influence be ascribed to humus 
under such circumstances, when it is not even known 
whether humus was ever contained in the soil? 

The method of culture in that district completely 
explains the permanent fertility. It appears very 
bad in the eyes of our agriculturists, but there it is 
the best plan which could be adopted. A field is 
cultivated once every three years and is in the 
intervals allowed to serve as a sparing pasture for 
cattle. The soil experiences no change in the two 
years during which it there lies fallow, further than 
that it is exposed to the influence of the weather, 
by which a fresh portion of the alkalies contained 
in it are again set free or rendered soluble. The 
animals fed on these fields yield nothing to these 
soils which they did not formerly possess. The 



COMPOSITION OF SOILS. 153 

weeds upon which they live spring from the soil, 
and that which they return to it as excrement must 
always be less than that which they extract. The 
fields, therefore, can have gained nothing from the 
mere feeding of cattle upon them ; on the contrary, 
the soil must have lost some of its constituents. 

Experience has shown in agriculture that wheat 
should not be cultivated after wheat on the same 
soil, for it belongs with tobacco to the plants which 
exhaust a soil. But if the humus of a soil gives it 
the power of producing corn, how happens it that 
wheat does not thrive in many parts of Brazil, where 
the soils are particularly rich in this substance, or 
in our own climate, in soils formed of mouldered 
wood ; that its stalk under these circumstances 
attains no strength, and droops prematurely? The 
cause is this, that the strength of the stalk is due 
to silicate of potash, and that the corn requires 
phosphate of magnesia, neither of which substances 
a soil of humus can afford, since it does not contain 
them; the plant may, indeed, under such circum- 
stances, become an herb, but will not bear fruit. 

Again, how does it happen that wheat does not 
flourish on a sandy soil, and that a calcareous soil is 
also unsuitable for its growth, unless it be mixed 
with a considerable quantity of clay?* It is because 
these soils do not contain alkalies in sufficient quan- 
tity, the growth of wheat being arrested by this 
circumstance, even should all other substances be 
presented in abundance. 

It is not mere accident that only trees of the fir 
tribe grow on the sandstone and limestone of the 
Carpathian mountains and the Jura, whilst we find 

* In consequence of these remarks in the former edition of this 
work. Professor Wohler of Gottingen has made several accurate analy- 
ses of different kinds of limestone belongingr to the secondary and 
tertiary formations. He obtained the remarkable result, that all those 
limestones, by the disintegration of which soils adapted for the culture 
of wheat are formed, invariably contain a certain quantity of potash. 
The same observation has also recently been made by M. Kuhlmann 
of Lille. The latter observed that the efflorescence on the mortar of 
walls consists of the carbonates of soda and potash. — L. 



154 THE ART OF CULTURE. 

on soils of gneiss, mica-slate, and granite in Bavaria, 
of clinkstone on the Rhone, of basalt in Vogelsberge, 
and of clay-slate on the Rhine and Eifel, the finest 
forests of other trees, which cannot be produced on 
the sandy or calcareous soils upon which pines 
thrive. It is explained by the fact that trees, the 
leaves of which are renewed annually, require for 
their leaves six or ten times more alkalies than 
the fir-tree or pine, and hence when they are placed in 
soils in which alkalies are contained in very small 
quantity, do not attain maturity.* When w^e see 
such trees growing on a sandy or calcareous soil — 
the red-beech, the service-tree, and the wild-cherry for 
example, thriving luxuriantly on limestone, we may 
be assured that alkalies are present in the soil, for 
they are necessary to their existence. Can we, then, 
regard it as remarkable that such trees should thrive 
in America, on those spots on which forests of pines 
which have grown and collected alkalies for centu- 
ries, have been burnt, and to which the alkalies are 
thus at once restored ; or that the Spartium scopari- 
ttni, Erysirmim latifolium, Blitum capitatum, Senecio 
viscosus, plants remarkable for the quantity of alka- 
lies contained in their ashes, should grow with the 
greatest luxuriance on the localities of conflagra- 
tions ?f 

Wheat will not grow on a soil which has produced 
wormwood, and, vice versa, wormwood does not 
thrive where wheat has grown, because they are 
mutually prejudicial by appropriating the alkalies 
of the soil. 

One hundred parts of the stalks of wheat yield 

* One thousand parts of the dry leaves of oaks yielded 55 parts of 
ashes, of which 2i parts consisted of alkalies soluble in water ; the 
same quantity of pine-leaves gave only 29 parts of ashes, which con- 
tain 4 6 parts of soluble salts. (De Saussure.) 

t After the great fire in London, large quantities of the Erysimum 
latifolium were observed growing on the spots where a fire had taken 
place. On a similar occasion the Blitum capitatum was seen at Copen- 
hagen, the Scnecio viscosiis in Nassau, and the Spartium scoparium. in 
Languedoc. After the burnings of forests of pines in North America, 
poplars grew on the same soil. — L. 



COMPOSITION OF SOILS. 155 

15-5 parts of ashes (H. Davy) ; the same quantity 
of the dry stalks of barley, 8.54 parts (Schrader) ; 
and one hundred parts of the stalks of oats, only 
4*42; — the ashes of all these are of the same com- 
position. 

We have in these facts a clear proof of what 
plants require for their growth. Upon the same 
field, which will yield only one harvest of wheat, two 
crops of barley and three of oats may be raised. 

AH plants of the grass kind require silicate of pot- 
ash. Now this is conveyed to the soil, or rendered 
soluble in it, by the irrigation of meadows. The 
eqiiisetacecB, the reeds and species of cane, for ex- 
ample, which contain such large quantities of silice- 
ous earth, or silicate of potash, thrive luxuriantly in 
marshes, in argillaceous soils, and in ditches, stream- 
lets, and other places where the change of water 
renews constantly the supply of dissolved silica. 
The amount of silicate of potash removed from a 
meadow in the form of hay is very considerable. We 
need only call to mind the melted vitreous mass 
found on a meadow between Manheim and Heidel- 
berg after a thunder-storm. This mass was at first 
supposed to be a meteor, but was found on examina- 
tion (by Gmelin) to consist of silicate of potash; 
a flash of lightning had struck a stack of hay, and 
nothing was found in its place except the melted 
ashes of the hay. 

Potash is not the only substance necessary for the 
existence of most plants; indeed it has been already 
shown that the potash may be replaced in many- 
cases by soda, magnesia, or lime ; but other sub- 
stances besides alkalies are required to sustain the 
life of plants. 

Phosphoric acid has been found in the ashes of all 
plants hitherto examined, and always in combination 
with alkalies or alkaline earths.* Most seeds con- 

* Professor Connall was lately kind enough to show me about half 
an ounce of a saline powder, which had been taken from an interstice 
in the body of a piece of teak timber. It consisted essentially of phos- 



156 THE ART OF CULTURE. 

tain certain quantities of phosphates. In the seeds 
of different kinds of corn particularly, there is abun- 
dance of phosphate of magnesia. 

Plants obtain their phosphoric acid from the soil. 
It is a constituent of all land capable of cultivation, 
and even the heath at Liineburg contains it in ap- 
preciable quantity. Phosphoric acid has been de- 
tected also in all mineral waters in which its pres- 
ence has been tested 3 and in those in which it has 
not been found it ha? not been sought for. The 
most superficial strata of the deposits of sulphuret 
of lead (^galena) contain crystallized phosphate of 
lead (^greenlead ore) ; clay-slate, which forms ex- 
tensive strata, is covered in many places with crys- 
tals of phosphate of alumina ( Wavellite) ; all its 
fractured surfaces are overlaid with it. Phosphate 
of lime (^Apatite) is found even in the volcanic 
boulders on the Laacher See in the Eifel, near 
Andernach.* 

The soil in which plants grow furnishes them with 
phosphoric acid, and they in turn yield it to animals, 
to be used in the formation of their bones, and of 
those constituents of the brain which contain phos- 
phorus. Much more phosphorus is thus afforded to 
the body than it requires, when flesh, bread, fruit, 
and husks of grain are used for food, and this ex- 
cess is eliminated in the urine and the solid excre- 
ments. We may form an idea of the quantity of 
phosphate of magnesia contained in grain, when 'we 
consider that the concretions in the caecum of horses 

phate of lime, with small quantities of carbonate of lime and phosphate 
of magnesia. This powder had been sent to Sir David Brewster from 
India, with the assurance that it was the same substance which usually 
is found in the hollows of teak timber. It has long been known that 
silica, in the form of tuhaslieer, is secreted by the bamboo; but I am 
not aware that phosphates have been found in the same condition. 
Without more precise information, we must therefore suppose that they 
are left in the hollows by the decny of the wood. Decay is a slow 
process of combustion, and the incombustible ashes must remain after 
the organic matter has been consumed. But if this explanation be cor- 
••ect, the wood of the teak-tree must contain an enormous quantity of 
earthy phosphates. — Ed. 

* See the analyses of soils in the Appendix. 



THE FERTILITY OF SOILS. 157 

consist of phosphate of magnesia and ammonia, 
which must have been obtained from the hay and oats 
consumed as food. Twenty-nine of these stones 
were taken after death from the rectum of a horse 
belonging to a miller, in Eberstadt, the total weight 
of which amounted to 3*3 lbs. ; and Dr. F. Simon has 
lately described a similar concretion found in the 
horse of a carrier, which weighed 1-6 lb. 

It is evident that the seeds of corn could not be 
formed without phosphate of magnesia, which is one 
of their invariable constituents ; the plant could not 
under such circumstances reach maturity. 

Some plants, however, extract other matters from» 
the soil besides silica, potash, and phosphoric acid,, 
which are essential constituents of the plants ordi- 
narily cultivated.* These other matters, we must 
suppose, supply, in part at least, the place and per- 
form the functions of the substances just named. 
We may thus regard common salt, sulphate of pot- 
ash, nitre, chloride of potassium, and other matters, 
as necessary constituents of several plants. 

Clay-slate contains generally small quantities of 
oxide of coppery and soils formed from micaceous- 
schist contain some metallic fluorides. Now, smalll 
quantities of these substances also are absorbed into 
plants, although we cannot affirm that they are 
necessary to them. 

It appears that in certain cases fluoride of calci- 
um f may take the place of the phosphate of lime in the 
bones and teeth ;| at least it is impossible otherwise- 
to explain its constant presence in the bones of 

* For more minute information regarding soils see the supplement 
tary chapter at the end of Part I. 

t Fluorine is the base of the acid contained in Fluor or Derbyshire 
spar ; with hydrogen it forms the hydrofluoric acid. The acid is separ.'- 
ated by heating fiuor spar with sulphuric acid, and is distinguished by 
its power of corroding glass, and of uniting with its silica. Compounds 
of Fluorine are called Fluorides, of the acid Hydrojluates . Calcium is 
the metallic base of lime. 

X The earthy parts of bones are composed principally of the phos- 
phate and carbonate of lime in various proportions, variable in different, 
cniinals, and mixed with small quantities, equally variable, of phos- 

]4 



158 THE ART OF CULTURE. 

antediluvian animals, by which they are distinguished 
from those of a later period. The bones of human 
skulls found at Pompeii contain as much fluoric acid 
as those of animals of a former world, for if they be 
placed in a state of powder in glass vessels, and 
digested with sulphuric acid, the interior of the 
vessel will, after twenty-four hours, be found power- 
fully corroded (Liebig) ; whilst the bones and teeth 
of animals of the present day contain only traces of 
it. (Berzelius.) 

De Saussure remarked, that plants require unequal 
quantities of the component parts of soils in different 
stages of their development ; an observation of much 
importance in considering the growth of plants. 
Thus, wheat yielded ^ggg of ashes a month before 
blossoming, j^g while in blossom, and j§§o after the 
ripening of the seeds. It is therefore evident, that 

phate of magnesia and fluate of lime. By acting upon calcined bones 
with sulphuric acid fluoric acid is disengaged. The following analyses 
of the bones of man and horned cattle, are given by Berzelius. 

Human bone. Ox bone. 

Cartilage soluble in water, . . . 32.17 ) o-, on 

Vessels 1.13 \ 

Subphosphate, and a little fluate of lime, . 

Carbonate of lime, .... 

Phosphate of magnesia, 

Soda and very little muriate of soda, 

100.00 ' 100.00 
The bones of man contain three times as much carbonate -of lime as 
those of the ox, and the latter are richer in phosphate of lime and 
magnesia in the same proportion. 

The following are the relative proportions of phosphate and carbonate 
of lime in bones of different animals, according to De Barros. 

Phosphate of Lime. Carbonate of Lime. 

Lion, 95.0 2.5 

Sheep, .... 80.0 19.3 

Hen, 88.9 10.4 

Frog, .... 95.2 2.4 

Fish, 91.9 5.3 



53.04 


57.35 


11.30 


3.85 


. 1.16 


2.05 


1.20 


3.45 



The enamel of the teeth is composed of 




Human. 


Ox. 


Phosphate of lime, . . . 88.5 


85.0 


Carbonate of " . . . 8.0 


7.1 


Phosphate of magnesia, . .1.5 


3.0 


Soda, 0.0 


1.4 


Membrane, alkali and water, . 2.0 


3.5 



100.0 100.0 



FALLOW-CROPS. 159 

wheat, from the time of its flowering, restores a part 
of its organic constituents to the soil, although the 
phosphate of magnesia remains in the seeds. 

The fallow-time, as we have already shown, is that 
period of culture during which land is exposed to a 
progressive disintegration by means of the influence 
of the atmosphere, for the purpose of rendering a 
certain quantity of alkalies capable of being appro- 
priated by plants. 

Now, it is evident, that the careful tilling of fal- 
low-land must increase and accelerate this disinte- 
gration. For the purpose of agriculture, it is quite 
indifferent, whether the land is covered with weeds, 
or with a plant which does not abstract the potash 
inclosed in it. Now many plants in the family of 
the leguminoscB are remarkable on account of the 
small quantity of alkalies or salts in general which 
they contain; the Windsor bean ( F«cm Paha),iov 
example, contains no free alkalies, and not one per 
cent, of the phosphates of lime and magnesia. 
(Einhof.) The bean of the kidney-bean {^Phaseohis 
vulgaris^ contains only traces of salts. (Braconnot.) 
The stem of Lucern [Medicago sativa) contains only 
0-83 per cent., that of the Lentil (^Ervum Lens) 
only 0*57 of phosphate of lime wdth albumen. 
(Crome.) Buck-wheat dried in the sun yields only 
0-681 per cent, of ashes, of which 0'09 parts are 
soluble salts. (Zenneck.)* These plants belong to 

* The small quantity of phosphates wliich the seeds of the lentils, 
beans, and peas contain, must be the cause of their small value as 
articles of nourishment, since they surpass all other vegetable food in 
the quantity of nitrogen which enters into their composition. But as 
the component parts of the bones (phosphate of lime and magnesia) 
are absent, they satisfy the appetite without increasing the strength. 
The following is an analysis of lentils (Playfair). 6-09"2 grammes lost 
0-972 grammes of water at 212°. 0.. 5(1(1 grammes, burned with oxide 
of copper, gave 0-910 grammes carbonic acid and 33G grammes of 
water. The lentils on combustion with oxide of copper, yielded a gas, 
in which the proportion of the nitrogen to the carbonic acid was 
as 1: 16. 

Carbon 44 45 

Hydrogen 6-59 

Nitrogen 6-42 

Water 15 95 



160 THE ART OF CULTURE. 

those which are termed fallow-crops, and the cause 
wherefore they do not exercise any injurious influ- 
ence on corn which is cultivated immediately after 
them is, that they do not extract the alkalies of the 
soil, and only a very small quantity of phosphates. 

It is evident that two plants growing beside each 
other will mutually injure one another, if they with- 
draw the same food from the soil. Hence it is not 
surprising that the wild chamomile {^Mati^icaria 
Chamoniilla) and Scotch broom {^Spartium Scopa- 
rium) impede the growth of corn, when it is con- 
sidered that both yield from 7 to 7-43 per cent, of 
ashes, which contain ^^ of carbonate of potash. The 
darnel and the fleabane {^Erigeron acre) blossom and 
bear fruit at the same time as corn, so that when 
growing mingled with it, they will partake of the 
component parts of the soil, and in proportion to 
the vigor of their growth, that of the corn must 
decrease ; for what one receives, the others are 
deprived of. Plants will, on the contrary, thrive 
beside each other, either when the substances neces- 
sary for their growth which they extract from the 
soil are of different kinds, or when they themselves 
are not both in the same stages of development at 
the same time. 

On a soil, for example, which contains potash, both 
wheat and tobacco may be reared in succession, 
because the latter plant does not require phosphates, 
salts which are invariably present in wheat, but re- 
quires only alkalies, and food containing nitrogen. 

According to the analysis of Posselt and Reimann, 
10,000 parts of the leaves of the tobacco-plant con- 
tain 16 parts of phosphate of lime, 8-8 parts of 
silica, and no magnesia; whilst an equal quantity 
of wheat straw contains 47*3 parts, and the same 
quantity of the grain of wheat 99-45 parts of phos- 
phates. (De Saussure.) 

Now, if we suppose that the grain of wheat is 
equal to half the weight of its straw, then the quan- 
tity of phosphates extracted from a soil by the same 



THE ALTERNATION OF CROPS. 161 

weights of wheat and tobacco must be as 97-7: 16. 
This difference is very considerable. The roots of 
tobacco, as well as those of wheat, extract the phos- 
phates contained in the soil, but they restore them 
again, because they are not essentially necessary to 
the development of the plant. 



CHAPTER VIII. 

ON THE ALTERNATION OF CROPS. 

It has long since been found by experience, that 
the growth of annual plants is rendered -imperfect, 
and their crops of fruit or herbs less abundant, by 
cultivating them in successive years on the same 
soil, and that, in spite of the loss of time, a greater 
quantity of grain is obtained when a field is allowed 
to lie uncultivated for a year. During this interval 
of rest, the soil, in a great measure, regains its 
original fertility. 

It has been further observed, that certain plants, 
such as peas, clover, and flax, thrive on the same 
soil only after a lapse of years ; whilst others, such 
as hemp, tobacco, helianthus tuberosus, rye, and oats, 
may be cultivated in close succession when proper 
manure is used. It has also been found, that several 
of these plants improve the soil, whilst others, and 
these are the most numerous, impoverish or exhaust 
it. Fallow turnips, cabbage, beet, spelt, summer 
and winter barley, rye and oats, are considered to 
belong to the class which impoverish a soil ; whilst 
by wheat, hops, madder, late turnips, hemp, poppies, 
teasel, flax, weld, and licorice, it is supposed to be 
entirely exhausted. 

The excrements of man and animals have been 

employed from the earliest times for the purpose of 

increasing the fertility of soils ; and it is completely 

established by all experience, that they restore cer- 

14* 



162 THE ALTERNATION OF CROPS. 

tain constituents to the soil, which are removed with 
the roots, fruit, or grain, or entire plants grown 
upon it. 

But it has been observed, that the crops are not 
always abundant in proportion to the quantity of 
manure employed, even although it may have been 
of the most powerful kind ; that the produce of 
many plants, for example, diminishes, in spite of the 
apparent replacement by manure of the substances 
removed from the soil, when they are cultivated on 
the same field for several years in succession. 

On the other hand it has been remarked, that a 
field which has become unfitted for a certain kind of 
plants was not on that account unsuited for another; 
and upon this observation, a system of agriculture 
has been gradually founded, the principal object of 
which is to obtain the greatest possible produce with 
the least expense of manure. 

Now it was deduced from all the foregoing facts, 
that plants require for their growth diiferent con- 
stituents of soil, and it was very soon perceived, 
that an alternation of the plants cultivated main- 
tained the fertility of a soil quite as well as leaving 
it at rest or fallow. It was evident, that all plants 
must give back to the soil in which they grow differ- 
ent proportions of certain substances, which are capa- 
ble of being used as food by a succeeding generation. 

But agriculture has hitherto never sought aid from 
chemical principles, based on the knowledge of those 
substances which plants extract from the soil on 
which they grow, and of those restored to the soil 
by means of manure. The discovery of such prin- 
ciples will be the task of a future generation, for 
what can be expected from the present, which recoils 
with seemino; distrust and aversion from all the 
means of assistance offered it by chemistry, and 
which does not understand the art of making a 
rational application of chemical discoveries ? A 
future generation, however, will derive incalculable 
advantage from these means of help. 



THEORY OF ITS USE. 163 

Of all ^;he views which have been adopted regard- 
ing the cause of the favorable effects of the alter- 
nations of crops, that proposed by M. Decandolle 
alone deserves to be mentioned as resting on a firm 
basis. 

Decandolle supposes, that the roots of plants 
imbibe soluble matter of every kind from the soil, 
and thus necessarily absorb a number of substances 
which are not adapted to the purposes of nutrition, 
and must subsequently be expelled by the roots, and 
returned to the soil as excrements. Now as excre- 
ments cannot be assimilated by the plant which eject- 
ed them, the more of these matters which the soil 
contains, the more unfertile must it be for the plants 
of the same species. These excrementitious matters 
may, however, still be capable of assimilation by 
another kind of plants, which would thus remove 
them from the soil, and render it again fertile for 
the first. And if the plants last grown also expel 
substances from their roots, which can be appropri- 
ated as food by the former, they will improve the 
soil in two ways. 

Now a great number of facts appear at first sight 
to give a high degree of probability to this view. 
Every gardener knows, that a fruit-tree cannot be 
made to grow on the same spot where another of the 
same species has stood ; at least not until after a 
lapse of several years. Before new vine-stocks are 
planted in a vineyard from which the old have been 
rooted out, other plants are cultivated on the soil 
for several years. In connexion with this it has 
been observed, that several plants thrive best when 
growing beside one another; and, on the contrary, 
that others mutually prevent each other's develop- 
ment. Whence it was concluded, that the beneficial 
influence in the former case depended on a mutual 
interchange of nutriment between the plants, and 
the injurious one in the latter on a poisonous action 
of the excrements of each on the other respectively.* 

* That these supposed exudations are uniformly more or less injuri- 



164 THE ALTERNATION OF CROPS. 

A series of experiments by Macaire-Princep gave 
great weight to this theory. He proved beyond all 
doubt, that many plants are capable of emitting ex- 
tractive matter from their roots. He found that the 
excretions were greater during the night than by 
day (?), and that the water in which plants of the 
family of the LeguminoscB grew acquired a brown 
color. Plants of the same species placed in water 
impregnated with these excrements were impeded in 
their growth, and faded prematurely, whilst, on the 
contrary, corn-plants grew vigorously in it, and the 
color of the water diminished sensibly; so that it 
appeared as if a certain quantity of the excrements 
of the LeguniinosfB had really been absorbed by the 
corn-plants. These experiments afforded, as their 
main result, that the characters and properties of the 
excrements of different species of plants are different 
from one another, and that some plants expel excre- 
mentitious matter of an acid and resinous character; 
others mild substances resemblina; o;um. The former 

o p 

of these, according to Macaire-Princep, may be re- 
garded as poisonous, the latter as nutritious. 

The experiments of Macaire-Princep afford posi- 
tive proof that the roots, probably of all plants, ex- 
pel matters, which cannot be converted in their or- 
ganism either into woody fibre, starch, vegetable al- 
bumen, or gluten, since their expulsion indicates that 
they are quite unfitted for this purpose. But they 

ous to plants of similar species, has been inferred from the fact, that a 
soil, in which peach or apple trees have grown, is unfit for young shoots 
of the same description, so as to render it a necessary rule in practice, 
that a piece of ground should be occupied by forest and by fruit trees 
alternately. 

Reference has also been made to a circumstance, which most travel- 
lers in the United States have remarked, and which I myself, during 
my tour in that country, had frequent opportunities of substantiating, 
namely, that where a forest of oak or of maple has been destroyed, the 
trees, that are apt to shoot up spontaneously in their place, are of the 
fir-tribe ; whereas, if a pine forest be cut down, young oaks and other 
allied species will make their appearance afterwards. — Daubeny's 
Lectures on .^tri-iculture. 

For an account of experiments on this subject now in progress at Ox- 
ford, see Appendix. 



THEORIES OF ITS USE. 165 

cannot be considered as a confirmation of the theory 
of Decandolle, for they leave it quite undecided 
whether the substances were extracted from the soil, 
or formed by the plant itself from food received from 
another source. It is certain, that the gummy and 
resinous excrements observed by Macaire-Princep 
could not have been contained in the soil, and as we 
know that the carbon of a soil is not diminished by 
culture, but, on the contrary, increased, we must 
conclude that all excrements which contain carbon 
must be formed from the food obtained by plants 
from the atmosphere. Now, these excrements are 
compounds, produced in consequence of the trans- 
formations of the food, and of the new forms which 
it assumes by entering into the composition of the 
various organs. 

M. Decandolle's theory is properly a modification 
of an earlier hypothesis, which supposed that the 
roots of different plants extracted different nutritive 
substances from the soil, each plant selecting that 
which was exactly suited for its assimilation. Ac- 
cording to this hypothesis, the matters incapable of 
assimilation are not extracted from the soil, whilst 
M. Decandolle considers that they are retur7ied to it 
in the form of excrements. Both views explain how 
it happens that after corn, corn cannot be raised 
with advantage, nor after peas, peas ; but they do 
not explain how a field is improved by lying fallow, 
and this in proportion to the care with which it is 
tilled and kept free from weeds ; nor do they show 
how a soil gains carbonaceous matter by the cultiva- 
tion of certain plants such as lucern and sainfoin. 

Theoretical considerations on the process of nutri- 
tion, as well as the experience of all agriculturists, 
so beautifully illustrated by the experiments of Ma- 
caire-Princep, leave no doubt that substances are 
excreted from the roots of plants, and that these 
matters form the means by which the carbon received 
from humus in the early period of their growth is 
restored to the soil. But we may now inquire wheth- 



166 THE ALTERNATION OF CROPS. 

er these excrements, in the state in which they are 
expelled, are capable of being employed as food by 
other plants. 

The excrements of a carnivorous animal contain 
no constituents fitted for the nourishment of another 
of the same species ; but it is possible that an her- 
bivorous animal, a fish, or a fowl, might find in them 
undigested matters capable of being digested in 
their organism, from the very circumstance of their 
organs of digestion having a different structure. 
This is the only sense in which we can conceive that 
the excrements of one animal could yield matter 
adapted for the nutrition of another. 

A number of substances contained in the food of 
animals pass through their alimentary organs without 
change, and are expelled from the system ; these are 
excrements but not excretions. Now a part of such 
excrementitious matter might be assimilated in pass- 
ing through the digestive apparatus of another ani- 
mal. The organs of secretion form combinations of 
which only the elements were contained in the food. 
The production of these new compounds is a conse- 
quence of the changes which the food undergoes in 
becoming chyle and chyme, and of the further trans- 
formations to w^hich these are subjected by entering 
into the composition of the organism. These mat- 
ters, likewise, are eliminated in the excrements, 
which must therefore consist of two different kinds 
of substances, namely, of the indigestible constitu- 
ents of the food, and of the new compounds formed 
by the vital process. The latter substances have 
been produced in consequence of the formation of 
fat, muscular fibre, cerebral and nervous substance, 
and are quite incapable of being converted into the 
same substances in any other animal organism. 

Exactly similar conditions must subsist in the vi- 
tal processes of plants. When substances which are 
incapable of being employed in the nutrition of a 
plant exist in the matter absorbed by its roots, they 
must be again returned to the soil. Such excrements 



CAUSES OF ITS BENEFICIAL INFLUENCE. 167 

mifht be serviceable and even indispensable to the 
existence of several other plants. But substances 
that are formed in a vegetable organism during the 
process of nutrition, which are produced, therefore, 
in consequence of the formation of woody fibre, 
starch, albumen, gum, acids, &,c., cannot again serve 
in any other plants to form the same constituents of 
vegetables. 

The consideration of these facts enables us to dis- 
tinguish the difference between the views of Decan- 
dolle and those of Macaire-Princep. The substances 
which the former physiologist viewed as excrements, 
belonged to the soil ; they were undigested matters, 
which although not adapted for the nutrition of one 
plant might yet be indispensable to another. Those 
matters, on the contrary, designated as excrements 
by Macaire-Princep, could only in one form serve for 
the nutrition of vegetables. It is scarcely necessary 
to remark, that this excremeutitious matter must un- 
dergo a change before another season. During au- 
tumn and winter it beg-ins to suffer a change from 
the influence of air and water ; its putrefaction, and 
at length, by continued contact with the air, which 
tillage is the means of procuring, its decay are effect- 
ed ; and at the commencement of spring it has be- 
come converted, either in w^hole or in part, into a 
substance which supplies the place of humus, by be- 
ing a constant source of carbonic acid. 

The quickness with w^hich this decay of the ex- 
crements of plants proceeds depends on the com- 
position of the soil, and on its greater or less po- 
rosity. It will take place very quickly in a calcareous 
soil : for the power of organic excrements to attract 
oxygen and to putrefy is increased by contact with 
the alkaline constituents, and by the general porous 
nature of such kinds of soil, which freely permit the 
access of air. But it requires a longer time in heavy 
soils consisting of loam or clay. 

The same plants can be cultivated with advantage 
on one soil after the second year, but in others not 



168 THE ALTERNATION OF CROPS. 

until the jfifth or ninth, merely on account of the 
change and destruction of the excrements, which 
have an injurious influence on the plants being com- 
pleted in the one, in the second year; in the others, 
not until the ninth. 

In some neighborhoods clover will not thrive till 
the sixth year, in others not till the twelfth ; flax in 
the second or third year. All this depends on the 
chemical nature of the soil, for it has been found by 
experience, that in those districts where the intervals 
at which the same plants can be cultivated with ad- 
vantage are very long, the time cannot be shortened 
even by the use of the most powerful manures. The 
destruction of the peculiar excrements of one crop 
must have taken place before a new crop can be 
produced. 

Flax, peas, clover, and even potatoes, are plants 
the excrements of which, in argillaceous soils, re- 
quire the longest time for their conversion into 
humus; but it is evident, that the use of alkalies 
and burnt lime, or even small quantities of ashes 
which have not been lixiviated, must enable a soil 
to permit the cultivation of the same plants in a 
much shorter time. 

A soil lying fallow owes its earlier fertility, in 
part, to the destruction or conversion into humus of 
the excrements contained in it, which is effected 
during the fallow season, at the same time that the 
land is exposed to a further disintegration. 

In the soils in the neio-hborhood of the Rhine and 
Nile, which contain much potash, and where crops 
can be obtained in close succession from the same 
field, the fallowing of the land is superseded by the 
inundation; the irrigation of meadows effects the 
same purpose. It is because the water of rivers and 
streams contains oxygen in solution, that it effects 
the most complete and rapid putrefaction of the ex- 
crements contained in the soil which it penetrates, 
and in which it is continually renewed. If it was 
the water alone which produced this effect, marshy 



CULTIVATION OF MEADOWS. 169 

meadows should be most fertile. Hence it is not 
sufficient in irrigating meadows to convert them into 
marshes, by covering for several months their sur- 
face with water, which is not renewed; for the 
advantage of irrigation consists principally in sup- 
plying oxygen to the roots of plants. The quantity 
of water necessary for this purpose is very small, so 
that it is sufficient to cover the meadow with a very 
thin layer, if this be frequently renewed. 

The cultivation of meado\vs forms one of the most 
important branches of rural economy. It contributes 
materially to the prosperity of the agriculturist by 
increasing his stock of cattle, and consequently by 
furnishing him with manure, which may be applied 
to the augmentation of his crops. Indeed, the great 
progress which has been made in Germany in the 
improvement of cattle is mainly attributable to the 
attention which is devoted in that country to the 
culture of meadow^s. The environs of Siegin, in 
Nassau, are particulary famed in this respect, and 
every year a large number of young farmers repair 
to it, for the purpose of studying this branch of 
agriculture iii situ. In that district the culture of 
grass has attained such great perfection, that the 
produce of their meadow-land far exceeds that ob- 
tained in any other part of Germany. This is effected 
simply by preparing the ground in such a manner as 
to enable it to be irrigated both in spring and in 
autumn. The surface of the soil is fitted to suit the 
locality, and the quantity of water which can be. 
commanded. Thus if the meadows be situated upon 
a declivity, banks of from one to two feet in height 
are raised at short distances from each other. The 
water is admitted by small channels upon the most 
elevated bank, and allowed to discharge itself over 
the sides in such a manner as to run upon the bank 
situated below. The grass grown upon meadows 
irrigated in this way is three or four times higher- 
than that obtained from fields which are covered with 
water that is deprived of all egress and renewal. 
15 



170 THE ALTERNATION OF CROPS. 

It follows from what has preceded, that the ad- 
vantage of the alternation of crops is owing to two 
causes. 

A fertile soil ought to afford to a plant all the in- 
organic bodies indispensable for its existence in suf- 
ficient quantity and in such condition as allows their 
absorption. 

All plants require alkalies, which are contained in 
some, in the Grmninem for example, in the form of 
silicates ; in others, in that of tartrates, citrates, 
acetates, or oxalates. 

When these alkalies are in combination with silicic 
acid, the ashes obtained by the incineration of the 
plant contain no carbonic acid ; but when they are 
united with organic acids, the addition of a mineral 
acid to their ashes causes an effervescence. 

A third species of plants requires phosphate of 
lime, another phosphate of magnesia, and several do 
not thrive without carbonate of lime. 

Silicic acid* is the first solid substance taken up 
by plants ; it appears to be the material from which 

* Silica, or siliceous earth, is the most abundant ingredient in the 
mineral kingdom, being one of the constituents of most rocks, and 
extensively distributed over the earth in the form of sand, quartz, 
carnelian, flint, &c., «fcc. It is also held in solution by the water 
of hot springs, as in the Geysers of Iceland, and the Azores, from 
which it is deposited, forming what is called siliceous sinter, and often 
incrusting the stems of plants and other bodies. The vegetable mat- 
ter in some instances has entirely disappeared, and the silica having 
taken its place we have silicified or petrified wood, &c. See Web- 
ster's Description of the Island of St. Michael, p. 208. From silica a 
substance is obtained which is considered as its base and called silicon 
and siliciitm. This base, combined with oxygen, constitutes silica, 
which is capable of combining with other bases ; from this and other 
properties it is called silicic acid. By combination with other sub- 
stances, as potash, soda, &c., silica becomes soluble in water. These 
compounds are called silicates. A white, earthy substance is found be- 
neath peat and in swampy lands and ponds, which has long been mis- 
taken for calcareous marl. It has been proved to consist of the siliceous 
skeletons of" infusorial vegetables, if tliey may be so called, or of those 
equivocal beings, which occupy the borders of the two kingdoms, and 
render it difficult, not to say impossible, to draw the line between 
them." This siliceous deposite has been found under nearly every peat 
bog in this country which has been examined. See Professor liailey's 
paper in American Journal of Science, Vol. XXXV p. 118, and Vol. 
XL. p. 174. 



CAUSES OF ITS BENEFICIAL INFLUENCE. 171 

the formation of the wood takes its origin, acting 
like a grain of sand around which the first crystals 
form in a solution of a salt which is in the act of 
crystallizing. Silicic acid appears to perform the 
function of woody fibre in the E qiiisetacece and bam- 
boos,* just as the crystalline salt, oxalate of lime, 
does in many of the lichens. 

When we ^row in the same soil for several years 
in succession different plants, the first of which 
leaves behind that which the second, and the second 
that which the third may require, the soil will be a 
fruitful one for all the three kinds of produce. If 
the first plant, for example, be wheat, which con- 
sumes the greatest part of the silicate of potash in a 
soil, whilst the plants which succeed it are of such 
a kind as require only small quantities of potash, as 
is the case with LeguminoscB, turnips, potatoes, &c., 
the wheat may be again sowed with advantage after 
the fourth year; for during the interval of three 
years the soil will, by the action of the atmosphere, 
be rendered capable of again yielding silicate of pot- 
ash in sufficient quantity for the young plants. 

The same precautions must be observed with re- 
gard to the other inorganic constituents, when it is 
desired to grow different plants in succession on the 
same soil : for a successive growth of plants which 
extract the same components parts, must gradually 
render it incapable of producing them. Each of 
these plants during its growth returns to the soil a 
certain quantity of substances containing carbon, 
which are gradually converted into humus, and are 
for the most part equivalent to as much carbon as 
the plants had formerly extracted from the soil in a 
state of carbonic acid. But although this is sufficient 
to bring many plants to maturity, it is not enough 
to furnish their different organs with the greatest 
possible supply of nourishment. Now the object of 

* Silica is found in the joints of bamboos, in the form of small round 
globules, which have received the name of Tubasheer, and are dis- 
tinguished by their remarkable optical properties. — Ed. 



172 THE ALTERNATION OF CROPS. 

agriculture is to produce either articles of commerce, 
Or food for man and animals ; but a maximum of 
produce in plants is always in proportion to the 
quantity of nutriment supplied to them in the first 
stage of their development. 

The nutriment of young plants consists of car- 
bonic acid, contained in the soil in the form of 
humus, and of nitrogen in the form of ammonia, 
both of which must be supplied to the plants, if the 
desired purpose is to be accomplished. The forma- 
tion of ammonia cannot be effected on cultivated 
land, but humus may be artificially produced ; and 
this must be considered as an important object in 
the alternation of crops, and as the second reason 
of its peculiar advantages. 

The sowing of a field with fallow plants, such as 
clover, rye, buck-wheat, &c., and the incorporation 
of the plants, when nearly at blossom, with the soil, 
affect this supply of humus in so far, that young 
plants subsequently growing in it find, at a certain 
period of their growth, a maximum of nutriment, 
that is, matter in the process of decay. 

The same end is obtained, but with much greater 
certainty, when the field is planted with sainfoin or 
lucern.* These plants are remarkable on account 
of the great ramification of their roots, and strong 
development of their leaves, and for requiring only 
a small quantity of inorganic matter. Until they 
reach a certain period of their growth, they retain 
all the carbonic acid and ammonia which may have 
been conveyed to them by rain and the air, for that 
which is not absorbed by the soil is appropriated by 
the leaves ; they also possess an extensive four or 

* The alternation of crops with sainfoin and lucern is now univer- 
sally adopted in Bingen and its vicinity, as well as in the Palatinate; 
the fields in these districts receive manure only once every nine years. 
In the first years after the land has been manured turnips are sown 
upon it, in the next following 3'eiiVs barley, with sainfoin or lucern; in 
the seventh year potatoes, in the eighth wheat, in the ninth barley; 
on the tenth year it is manured, and then the same rotation again takes 
place. — L. 



CAUSES OF ITS BENEFICIAL INFLUENCE. 173 

six-fold surface, capable of assimilating these bodies, 
and of preventing the volatilization of the ammonia 
from the soil, by completely covering it in. 

An immediate consequence of the production of 
the green principle of the leaves, and of their re- 
maining component parts, as well as those of the 
stem, is the equally abundant excretion of organic 
matters into the soil from the roots. 

The favorable influence which this exercises on the 
land, by furnishing it with matter capable of being 
converted into humus, lasts for several years, but 
barren spots gradually appear after the lapse of 
some time. Now it is evident that, after from six 
to seven years, the ground must become so impreg- 
nated with excrements, that every fibre of the root 
will be surrounded with them. As they remain for 
some time in a soluble condition, the plants must 
absorb part of them and sufl'er injurious effects in 
consequence, because they are not capable of assim- 
ilation. When such a field is observed for several 
years, it is seen that the barren spots are again cov- 
ered with vegetation, (the same plants being always 
supposed to be grown,) whilst new spots become 
bare and apparently unfruitful, and so on alternately. 
The causes which produce this alternate barrenness 
and fertility in the different parts of the land are 
evident. The excrements upon the barren spots 
receiving no new addition, and being subjected to 
the influence of air and moisture, they pass into 
putrefaction, and their injurious influence ceases. 
The plants now find those substances which formerly 
prevented their growth removed, and in their place 
meet with humus, that is, vegetable matter in the act 
of decay. 

We can scarcely suppose a better means of pro- 
ducing humus than by the growth of plants, the 
leaves of which are food for animals ; for they pre- 
pare the soil for plants of every other kind, but 
particularly for those to which, as to rape and flax, 
15* 



174 OF MANURE. 

the presence of humus is the most essential condi- 
tion of growth. 

The reasons why this interchange of crops is so 
advantageous, — the principles which regulate this 
part of agriculture, are, therefore, the artificial pro- 
duction of humus, and the cultivation of different 
kinds of plants upon the same field, in such an order 
of succession, that each shall extract only certain 
components of the soil, whilst it leaves behind or 
restores those which a second or third species of 
plant may require for its growth and perfect devel- 
opment. 

Now, although the quantity of humus in a soil may 
be increased to a certain degree by an artificial 
cultivation, still, in spite of this, there cannot be the 
smallest doubt that a soil must gradually lose those 
of its constituents which are removed in the seeds, 
roots, and leaves of the plants r«,ised upon it. The 
fertility of a soil cannot remain unimpaired, unless 
we replace in it all those substances of which it has 
been thus deprived. 

Now this is effected by manure. 



CHAPTER IX. 

OF MANURE. 

When it is considered that every constituent of 
the body of man and animals is derived from plants, 
and that not a single element is generated by the 
vital principle, it is evident that all the inorganic 
constituents of the animal organism must be re- 
garded, in some respect or other, as manure. During 
their life, the inorganic components of plants which 
are not required by the animal system, are disen- 
gaged from the organism, in the form of excrements. 
After their death, their nitrogen and carbon pass 
into the atmosphere as ammonia and carbonic acid, 



ANIMAL MANURE. 175 

the products of their putrefaction, and at last noth- 
ing remains except the phosphate of lime and other 
salts in their bones. Now this earthy residue of the 
putrefaction of animals must be considered, in a 
rational system of agriculture, as a powerful manure 
for plants, because that which has been abstracted 
from a soil for a series of years must be restored to 
it, if the land is to be kept in a permanent condition 
of fertility. 



ANIMAL MANURES. 



We may now inquire whether the excrements of 
animals, which are employed as manure, are all of 
a like nature and power, and whether they, in every 
case, administer to the necessities of a plant by an 
identical mode of action. These points may easily 
be determined by ascertaining- the composition of 
the animal excrements, because we shall thus learn 
what substances a soil really receives by their means. 
According to the common view, the action of solid 
animal excrements depends on the decaying organic 
matters which replace the humus, and on the pres- 
ence of certain compounds of nitrogen, which are 
supposed to be assimilated by plants, and employed 
in the production of gluten and other azotized sub- 
stances. But this view requires further confirmation 
with respect to the solid excrements of animals, for 
they contain so small a proportion of nitrogen, that 
they cannot possibly by means of it exercise any 
influence upon vegetation. 

We may form a tolerably correct idea of the chem- 
ical nature of the animal excrement without further 
examination, by comparing the excrements of a dog 
with its food. When a dog is fed with flesh and 
bones, both of which consist in great part of organic 
substances containing nitrogen, a moist white excre- 
ment is produced which crumbles gradually to a dry 
powder in the air. This excrement consists of the 



176 OF MANURE. 

phosphate of lime of the bones, and contains scarce- 
ly jig part of its weight of foreign organic substan- 
ces. The whole process of nutrition in an animal 
consists in the progressive extraction of all the ni- 
trogen from the food, so that the quantity of this 
element found in the excrements must always be less 
than that contained in the nutriment. The analysis 
of the excrements of a horse by Macaire and Marcet 
proves this fact completely. The portion of excre- 
ments subjected to analysis was collected whilst 
fresh, and dried in vacuo over sulphuric acid ; 100 
parts of it (corresponding to from 350 to 400 parts 
of the dung before being dried) contained 0-8 of 
nitrogen. Now every one who has had experience 
in this kind of analysis is aware, that a quantity un- 
der one per cent, cannot be determined with accura- 
cy. We should, therefore, be estimating its propor- 
tion at a maximum, were we to consider it as equal 
to one-half per cent. It is certain, however, that 
these excrements are not entirely free from nitrogen, 
for they emit ammonia when digested with caustic 
potash. 

The excrements of a cow, on combustion with ox- 
ide of copper, yielded a gas which contained one 
vol. of nitrogen gas, and 26-30 vol. of carbonic acid. 

100 parts of fresh excrements' contained 

Nitrogen 0-506 

Carbon 6-204 

Hydrogen 0-824 

Oxygen . . ' . . . 4-818 

Ashes 1-748 

Water . . . . . . 85-900 

100-000 

Now, according to the analysis of Boussingault, 
which merits the greatest confidence, hay contains 
one per cent, of nitrogen; consequently in the 25 lbs. 
of hay which a cow consumes daily, | of a lb. of ni- 
trogen must have been assimilated. This quantity 
of nitrogen entering into the composition of muscu- 
lar fibre would yield 8-3 lbs. of flesh in its natural 



ITS ESSENTIAL ELEMENTS. 177 

condition.* The daily increase in size of a cow is, 
however, much less than this quantity. We find that 
the nitrogen, apparently deficient, is actually con- 
tained in the milk and urine of the animal. The 
urine of a milch-cow contains less nitrogen than that 
of one which does not yield milk; and as long as a 
cow yields a plentiful supply of milk, it cannot be 
fattened. We must search for the nitrog-en of the 
food assimilated, not in the solid, but in the liquid 
excrements. The influence which the former exer- 
cise on the growth of vegetables does not depend 
upon the quantity of nitrogen which they contain. 
For if this were the case, hay should possess the 
same influence ; that is, from 20 to 25 lbs. ought to 
have the same power as 100 lbs. of fresh cow-dung. 
But this is quite opposed to all experience. 

Which then are the substances in the excrements 
of the cow and horse which exert an influence on 
vegetation? 

When horse-dung is treated with water, a portion 
of it to the amount of 3 or 3J per cent, is dissolved, 
and the water is colored yellow. The solution is 
found to contain phosphate of magnesia, and salts 
of soda, besides small quantities of organic matters.f 

* 100 lbs. of flesh contain on an average 15-86 of muscular fibre : 18 
parts of nitrogen are contained in 100 parts of the latter. — L. 

The flesh of animals when digested in repeated portions of cold wa- 
ter, affords albumen, saline substances, and coloring and extractive 
matters. When the part that is no longer acted on by cold water is di- 
gested in hot water, the cellular substance is removed in the form of 
gelatine, and fatty matter separates. The insoluble residue is princi- 
pally ^//77«e. 

The following is the proportion of water, albumen, and gelatine in 
the muscular parts of several animals and fishes. 



100 parts of 




A/bi 


•imen or 






Total of 


Muscle of 


Water. 


Fibrine. 


Gelatine. 


Nutritive Matter, 


Beef, 


74 




20 


6 




26 


Veal, 


75 




19 


6 




25 


Mutton, 


71 




22 


7 




29 


Pork, 


76 




19 


5 




24 


Chicken, 


73 




20 


7 




27 


Cod, 


79 




14 


7 




21 


Haddock, 


82 




13 


5 




18 






See B 


rande's 


Chemistry, 4th 


edit.. 


,p. 1184. 


t Dr. C. T. 


Jackson 


in his " 


• Geological and Jlgriculturai 


' Surveri of 


Rhode Islund, 


" (page 205,) give 


s the foil 


owing analysis 


of horse-dung: 



178 OF MANURE. 

The portion of the dung undissolved by the water 
yields to alcohol a resinous substance possessing all 
the characters of gall which has undergone some 
change; while the residue possesses the properties 
of sawdust, from which all soluble matter has been 
extracted by water, and burns without any smell. 
100 parts of the fresh dung of a horse being dried at 
100° C. (212^ F.) leave from 25 to 30 or 31 parts of 
solid substances, and contained, accordingly, from 
69 to 75 parts of water. From the dried excrements, 
we obtain, by incineration, variable quantities of salts 
and earthy matters according to the nature of the 
food which has been taken by the animal. Macaire 
and Marcet found 27 per cent, in the dung analyzed 
by them ; I obtained only 10 per cent, from that of 
a horse fed with chopped straw, oats, and hay. It 
results then that with from 3900 to 4400 lbs. of fresh 
horse-dung, corresponding to 110 lbs. of dry dung, 
we place on the land from 2737 to 3006 lbs. of wa- 
ter, and from 804 to 992 lbs. of vegetable matter and 
altered gall, and also from 110 to 297 lbs. of salt 
and other inorganic substances. 

The latter are evidently the substances to which 
our attention should be directed, for they are the 
same which formed the component parts of the hay, 
straw, and oats with which the horse was fed. Their 

— 500 grains,, dried at a heat a little above that of boiling water, lost 
357 grains of water. The dry mass weighing 143 grains was burned, 
and left 8 grains of ashes, of which 4-8U grains were soluble in dilute 
nitric acid, and 3 "20 insoluble. The ashes being analyzed, gave 

Silica 3-2 

Phosphate of lime 0-4 

Carbonate of lime . . . . . 1-5 
Phosphate of magnesia and soda . . 29 

80 
It consists, then, of the following ingredients : — 

Water 3570 

Vegetable fibre and animal matter . 1350 

Silica ....... 3'2 

Phosphate of lime .... 0-4 

Carbonate of lime ..... 1-5 

Phosphate of magnesia and soda . . 29 

500 



ITS ESSENTIAL ELEMENTS. 179 

principal constituents are the phosphates of lime and 
magnesia, carbonate of lime and silicate of potash ; 
the first three of these preponderated in the corn, 
the latter in hay. 

Thus in 1102 lbs. of horse-dung, we present to a 
field the inorganic substances contained in 6612 lbs. 
of hay, or 9146 lbs. of oats (oats containing 3*1 per 
cent, ashes according to De Saussure). This is suf- 
ficient to supply 1| crop of wheat with potash and 
phosphates. 

The excrements of cows,* black cattle, and sheep, 
contain phosphate of lime, common salt, and silicate 
of lime, the weight of which varies from 9 to 28 per 
cent., according to the fodder which the animal re- 
ceives ; the fresh excrements of the cow contain from 
86 to 90 per cent, of water. 

Human faces have been subjected to an exact 
analysis by Berzelius. When fresh they contain, be- 
sides I of their weight of water, nitrogen in very 
variable quantity, namely, in the minimum 1|, in the 
maximum 5 per cent. In all cases, however, they 
were richer in this element than the excrements of 
other animals. Berzelius obtained by the incinera- 
tion of 100 parts of dried excrements, 15 parts of 
ashes, which were principally composed of the phos- 
phates of lime and magnesia. 

The following quantitative organic analysis has 
recently been executed for the purpose of ascertain- 

* It has been formerly stated (page 120), that all the potash contained 
in the food of a cow is again discharged in its excrements. The same 
also takes place with the other inorganic constituents of food, either 
when they are not adapted for assimilation, or when present in supera- 
bundant quantities. The value of manure may thus be artificially in- 
creased. We lately saw, for example, some cow-dung, sent by a farm- 
er, who wished to ascertain the cause of its increased value. Ho had 
formerly employed this manure for his land, but with so little advan- 
tage that he found it more profitable to dry it, and use it as fuel. On 
inquiry, it was found, that his cows had been fed upon oil-cakes. This 
species of food is particularly rich in phosphates. More of these salts 
being present tiian were requisite for the purpose of assimilation, they 
were removed from the system in the form of excrementitious matter, 
and in a condition adapted for the uses of plants. The fact that partic- 
ular kinds of food enrich or impoverish the manure obtained from the 
cattle fed upon them, has repeatedly been observed. — Ed. 



180 OF MANURE. 

ing the proportion of carbon, nitrogen, and inorganic 
matter contained in faeces, in comparison with the 
food taken.* (Playfair.) 

Carbon 45-24 

Hydrogen 6-88 

Nitrogen (average) 4 00 

Oxygen 30-30 

Ashes . . . . . . . . 13-58 

The inorganic matter contained in the excrements 
analyzed is nearly two per cent, less than that found 
by Berzelius ; but the proportion always varies, ac- 
cording to the nature of the food. 

It is quite certain, that the vegetable constituents 
of the excrements with which we manure our fields 
cannot be entirely without influence upon the growth 
of the crops on them, for they will decay, and thus 
furnish carbonic acid to the young plants. But it 
cannot be imagined that their influence is very great, 
when it is considered that a good soil is manured 
only once every six or seven years, or once every 
eleven or twelve years, when sainfoin or lucern has 
been raised on it, that the quantity of carbon thus 
given to the land corresponds to only 5*8 per cent, 
of what is removed in the form of herbs, straw, and 
grain ; and further that the rain-water received by a 
soil contains much more carbon in the form of car- 
bonic acid than these vegetable constituents of the 
manure. , 

The peculiar action then, of the solid excrements j 
is limited to their inorganic constituents, which thus 
restore to a soil that which is removed in the form i 
of corn, roots, or grain. When we manure land with, 
the dung of the cow or sheep, we supply it with? 
silicate of potash and some salts of phosphoric acid, i 
In human faeces we give it the phosphates of lime 
and magnesia; and in those of the horse, phosphate 

* The details of the analysis are as follows: — 2-356 grammes lefl 
0320 gramme ashes after incineration ; these consisted of the pjiosphate 
of lime and magnesia. 0352 gramme yielded, on combustion with 
oxide of copper, 576 gram, carbonic acid, and 218 gram, water. 
(L. P.) 



ITS ESSENTIAL ELEMENTS- 181 

of magnesia, and silicate of potash. In the straw 
which has served as litter, we add a further quantity 
of silicate of potash and phosphates; which, if the 
straw be putrefied, are in exactly the same condition 
in which they were before being assimilated. 

It is evident, therefore, that the soil of a field will 
alter but little, if we collect and distribute the dung 
carefully ; a certain portion of the phosphates, how- 
ever, must be lost every year, being removed from the 
land with the corn and cattle, and this portion will 
accumulate in the neighborhood of large towns. The 
loss thus suffered must be compensated for in a well- 
managed farm, and this is partly done by allowing 
the fields to lie in grass. In Germany, it is con- 
sidered that for every 100 acres of corn land, there 
must, in order to effect a profitable cultiA^ation, be 
20 acres of pasture-land, which produce annually, on 
an average, 551 lbs. of hay. Now assuming that 
the ashes of the excrements of the animals fed with 
this hay amount to 6*82 per cent., then 376 lbs. of 
the silicate of lime and phosphates of magnesia and 
lime must be yielded by these excrements, and will 
in a certain measure compensate for the loss which 
the corn-land had sustained. 

The absolute loss in the salts of phosphoric acid, 
which are not again replaced, is spread over so great 
an extent of surface, that it scarcely deserves to be 
taken account of. But the loss of phosphates is 
again replaced in the pastures by the ashes of the 
wood used in our houses for fuel. 

We could keep our fields in a constant state of 
fertility by replacing every year as much as we re- 
move from them in the form of produce ; but an in- 
crease of fertility, and consequent increase of crop 
can only be obtained when we add more to them 
than we take away. It will be found, that of two 
fields placed under conditions otherwise similar, the 
one will be most fruitful upon which the plants are 
enabled to appropriate more easily and in greater 
16 



182 OF MANURE. 

abundance those contents of the soil which are 
essential to their growth and development. 

From the foregoing remarks it will readily be in- 
ferred, that for animal excrements, other subtances 
containing their essential constituents may be sub- 
stituted. In Flanders, the yearly loss of the necessary 
matters in the soil is completely restored by covering 
the fields with ashes of wood or bones, which may 
or may not have been lixiviated * and of which the 
greatest part consists of the phosphates of lime and 
magnesia. The great importance of manuring with 
ashes has been long recognised by agriculturists as 
the result of experience. So great a value, indeed, 
is attached to this material in the vicinity of Mar- 
burg and in the Wetterau,t that it is transported as 
a manure from the distance of 18 or 24 miles. J Its 
use will be at once perceived, when it is considered 
that the ashes, after having been washed with water, 
contain silicate of potash exactly in the same pro- 
portion as in straw (10 Si O 3 -)- K 0.), and that 
their only other constituents are salts of phosphoric 
acid. 

But ashes obtained from various kinds of trees are 
of very unequal value for this purpose; those from 
oak-wood are the least, and those from beech the 
most serviceable. The ashes of oak-wood contain 
only traces of phosphates, those of beech the fifth 
part of their weight, and those of the pine and fir 
from 9 to 15 per cent. The ashes of pines from 
Norway contain an exceedingly small quantity of 
phosphates, namely, only 1-8 per cent, of phosphoric 
acid. (Berthier.) § 

* Lixi.viation signifies the removal by water of the soluble alkaline or 
saline matters in any earthy mixture ; as from that of lime and potash, 
or from ashes to obtain a ley. 

t Two well known agricultural districts; the first in Hesse-Cassel, 
the second in Hesse-Darmstadt. — Trans. 

\ Ashes are used with great advantage on the light siliceous soil of 
Long Island, Connecticut, and various other places in the United 
States. 

§ " The e.'^istence of phosphate of lime in the forest soils of the United 
States, is proved not only by its existence in the pollen of the pinus 



BONE MANURE. 183 

With every 110 lbs. of the lixiviated ashes of the 
beech which we spread over a soil, we furnish as 
much phosphates as 507 lbs. of fresh human excre- 
ments could yield. Again, according to the analysis 
of De Saussure, 100 parts of the ashes of the grain 
of wheat contain 32 parts of soluble, and 44*5 of 
insoluble phosphates, in all 76-5 parts. Now the 
ashes of wheat straw contain 11*5 per cent, of the 
same salts; hence with every 110 lbs. of the ashes 
of the beech, we supply a field with phosphoric acid 
sufficient for the production of 4210 lbs. of straw^ 
(its ashes being calculated at 4*3 per cent, De 
Saussure), or for 16-20000 lbs. of corn, the ashes of 
which amount, according to De Saussure, to 1*3 per 
cent. 

Bone manure possesses a still greater importance 
in this respect. The primary sources from which 
the bones of animals are derived are, the hay, straw, 
or other substances which they take as food. Now 
if we admit that bones contain 55 per cent, of the 
phosphates of lime and magnesia (Berzelius), and 
that hay contains as much of them as wheat stra\t, 
it will follow that8*81bs. of bones contain as much 
phosphate of lime as 1102 lbs. of hay or wheat- 
straw, and 2-2 lbs. of it as much as 1102 lbs. of the 
grain of wheat or oats. These numbers express 
pretty nearly the quantity of phosphates which a 
soil yields annually on the growth of hay and corn. 
Now the manure of an acre of land with 44 lbs. of 
bone dust is sufficient to supply three crops of wheat, 

abies (which is composed of 3 per cent, phosphate of Jime and potash), 
but by its actual detection in the ashes of pines and other trees. — 10' I 
parts of the ashes of loood ofpinus abies give 3 per cent, phosphate of 
iron; 100 parts of the ashes of the coal of pinus sytvestris give 172 
phosphate of lime, 0*'25 phosphate of iron ; 100 parts of ashes of oak 
coal give 7-1 phosphate of lime, 3-7 phosphate of iron ; 100 parts of the 
aslies of bass w^ood give 5 4 phosphate of lime, 3*2 phosphate of iron ; 
100 parts of the ashes of birch wood give 7-3 phosphate of lime, 1-25 
phosphate of iron; 100 parts of the ashes of oak wood give 1-8 phos- 
phate of lime ; 100 parts of the ashes of alder coal give 345 phosphate 
of linie, 9 phosphate of iron. These are the calculated results from 
Berthier"s analyses." — Dr. S. L. Dana, in Report on a Reexamination 
of the Economical Geology of Massachusetts. 



184 OF MANURE. 

clover, potatoes, turnips, &c., with phosphates. But 
the form in which they are restored to a soil does 
not appear to be a matter of indifference. For the 
more finely the bones are reduced to powder, and 
the more intimately they are mixed with the soil, 
the more easily are they assimilated. The most easy 
and practical mode of effecting their division is to 
pour over the bones, in a state of fine powder, half 
of their weight of sulphuric acid diluted with three 
or four parts of water, and after they have been 
digested for some time, to add one hundred parts 
of water, and sprinkle this mixture over the field 
before the plough. In a few seconds, the free acids 
unite wuth the bases contained in the earth, and a 
neutral salt is formed in a very fine state of division. 
Experiments instituted on a soil formed from grau- 
wacke, for the purpose of ascertaining the action of 
manure thus prepared, have distinctly shown that 
neither corn, nor kitchen-garden plants, suffer in- 
jurious effects in consequence, but that on the con- 
trary they thrive with much more vigor. 

It has also been found, that bones act more speed- 
ily and efficaciously after being boiled. This is 
probably owing to the removal of fatty matter, the 
presence of which impedes the putrefaction of the 
gelatin contained in them. 

In the manufactories of glue, many hundred tons 
of a solution of phosphates in muriatic acid are 
yearly thrown away as being useless. It would be 
important to examine whether this solution might 
not be substituted for the bones. The free acid 
would combine with the alkalies in the soil, espec- 
ially with the lime, and a soluble salt would thus be 
produced, which is known to possess a favorable 
action upon the growth of plants. This salt, muriate 
of lime (or chloride of calcium), is one of those 
compounds which attracts water from the atmosphere 
with great avidity, and in dry lands might advan- 
tageously supply the place of gypsum in decompos- 
ing carbonate of ammonia, with the formation of 



EXPLANATION OF ITS ACTION. 185 

sal-ammoniac and carbonate of lime. A solution of 
bones in muriatic acid placed on land in autumn or 
in winter would, therefore, not only restore a neces- 
sary constituent of the soil, and attract moisture to 
it, but would also give it the power to retain all the 
ammonia which fell upon it dissolved in the rain 
during the period of six months.* 

The ashes of brown coalf and peat often contain 
silicate of potash, J so that it is evident, that these 

* Immense quantities of bran are used in all print-works, for the 
purpose of clearing printed goods. After having served this purpose, 
it is throvi^n away. But the insoluble part of bran contains much 
phosphates of magnesia and soda ; it would therefore be useful to pre- 
serve it as a manure. This has been done for some years in a farm 
with which I am connected, and its value as a manure has been found 
so great that it is much preferred to cow-dung. In some works this 
waste bran is heaped up into little hillocks, which might be disposed 
of as a manure, instead of being an annoyance on account of the space 
which it occupies. — Ed. 

t Brown coal. Braunkohle, Lignite has the structure and appearance 
of carbonized wood. It occurs abundantly in Germany ; in Hessia it 
forms beds 20 to 40 feet thick, and several square miles in extent. 
Fibrous and compact varieties occur near Bovey Tracey in England, 
where it is called Bovey coal. Small quantities are found at Gay Head, 
Massachusetts. 

t The following is the result of an analysis by Dr. C. T. Jackson, 
of peat from Lexington, Massachusetts. 100 grains, dried at 300° F. 
weighed 74 grains, loss 26 grains, water. Burned in a platina crucible 
it left 5-0 ashes. The ashes yielded 

Silex, 10 

Alumina, iron, and manganese, . . . 0-6 

Phosphate of lime, 30 

Potash, traces. 

46 
Peat from Watertown, Massachusetts, yielded 4-5 grains of ashes, 
which gave by analysis 

Silex, '. 1-3 

Alumina, oxide of iron, and manganese, . , 1-5 
Phosphate of lime, 1-7 

4-5 
The vegetable matter amounted to 95 5 per cent., consisting of veg- 
etable fibre, and apocrenic and crenic acids, in part combined with the 
bases obtained from its ashes. See Report on Rhode Island, p. 233. 

Sioamp -rmtck contains the same ingredients as peat, but the vegetable 
matters are more finely divided, more soluble, and there is generally a 
larger proportion of earthy matters. It is formed of the fine particles 
of humus, washed out from the upland soils, and of the dead and 
decomposed leaves and roots of sv/amp plants. 

The pulpy matter of both peat and swamp muck consists chiefly of 
the apocrenic acid, in part combined with the earthy bases, and me- 
tallic oxides. The crenic acid is frequently united with lime and man- 

16* 



186 OF MANURE. 

might completely replace one of the principal con- 
stituents of the dung of the cow and horse, and 
they contain also some phosphates. Indeed, they 
are much esteemed in the Wetterau as manure for 
meadows and moist land. 

It is of much importance to the agriculturist, that 
he should not deceive himself respecting the causes 
which give the peculiar action to the substances just 
mentioned. It is known that they possess a very 
favorable influence on vegetation ; and it is likewise 
certain that the cause of this is their containing a 
body, which, independently of the influence which 
it exerts by virtue of its form, porosity, and capabil- 
ity of attracting and retaining moisture, also assists 
in maintaining the vital processes in plants. If it 
be treated as an unfathomable mystery, the nature 
of this aid will never be known. 

In medicine, for many centuries, the mode of 
action of all remedies was supposed to be concealed 
by the mystic veil of Isis, but now these secrets 
have been explained in a very simple manner. An 
unpoetical hand has pointed out the cause of the 
wonderful and apparently inexplicable healing vir- 
tues of the springs in Savoy, by which the inhabi- 
tants cured their goitre ; it was shown that they 
contain small quantities of iodine. In burnt sponges 
used for the same purpose, the same element was 
also detected. The extraordinary efficacy of Peru- 
vian bark was found to depend on a small quantity 
of a crystalline body existing in it, viz. quinine; and 
the causes of the various eff"ects of opium were 
detected in as many diff"erent ingredients of that 
drug. 

Calico-printers used for a long time the solid 
excrements of the cow, in order to brighten and 
fasten colors on cotton goods ; this material ap- 

fanese ; iron and matjnesia occur in several of the peats analyzed, 
hosphoric acid also exists in them, both in its free state, and in com- 
bination with lime and magnesia. In some peats Dr. J. found traces 
of oxalic acid and oxalates. lOUL, 210. See Appendix, for Peat 
compost. 



EXPLANATION OF ITS ACTION. 187 

peared quite indispensable, and its action was as- 
cribed to a latent principle which it had obtained 
from the living organism. But since its action was 
known to depend on the phosphates contained in it, 
it has been completely replaced by a mixture of 
salts, in which the principal constituents are the 
phosphates of soda and lime.* 

Now all such actions depend on a definite cause, by 
ascertaining which we place the actions themselves 
at our command. 

It must be admitted as a principle of agriculture, 
that those substances which have been removed from 
a soil must be completely restored to it, and whether 
this restoration be effected by means of excrements, 
ashes, or bones, is in a great measure a matter of 
indifference. A time will come when fields will be 
manured with a solution of glass f (silicate of pgt- 
ash), with the ashes of burnt straw, and with salts 
of phosphoric acid, prepared in chemical manufac- 
tories, exactly as at present medicines are given for 
fever and goitre. 

There are some plants which require humus, and 
do not restore it to the soil by their excrements ; 
whilst others can do without it altogether, and add 
humus to a soil which contains it in small quantity. 
Hence a rational system of agriculture would employ 
all the humus at command for the supply of the 
former, and not expend any of it for the latter ; and 
would in fact make use of them for supplying the 
others with humus. 

We have now considered all that is requisite in a 
soil, in order to furnish its plants with the materials 
necessary for the formation of the woody fibre, the 

* This mixture of salts is sold to calico-printers in large quantities 
under the name of "dung substitute." It would be well worth experi- 
ment to try its effects as a manure upon land. Its cost is 3d. or 4d. per 
pound, and is not, therefore, dearer than nitrate of soda, which is now 
so extensively used. — Ed. 

t When glass contains a very large proportion of potash, it is soluble 
in boiling water ; and by combination with other substances, silica 
becomes soluble in water. According to Dr. Jackson, crenic acid 
enables water to take it up. 



188 OF MANURE. 

grain, the roots, and the stem, and now proceed to 
the consideration of the most important object of 
agriculture, viz. the production of nitrogen in a form 
capable of assimilation, — the production, therefore, 
of substances containing this element. The leaves, 
which nourish the woody matter, the roots, from 
which the leaves are formed, and which prepare the 
substances for entering into the composition of the 
fruit, and, in short, every part of the organism of a 
plant, contain azotized matter in very varying pro- 
portions, but the seeds and roots are always partic- 
ularly rich in them. 

Let us now examine in what manner the greatest 
possible production of substances containing nitro- 
gen can be effected. Nature, by means of the atmo- 
sphere, furnishes nitrogen to a plant in quantity suffi- 
cient for its normal growth. Now its growth must 
be considered as normal, when it produces a single 
seed capable of reproducing the same plant in the 
following year. Such a normal condition would suf- 
fice for the existence of plants, and prevent their 
extinction, but they do not exist for themselves 
alone ; the greater number of animals depend on the 
vegetable world for food, and by a wise adjustment 
of nature, plants have the remarkable power of con- 
verting, to a certain degree, all the nitrogen offered 
to them into nutriment for animals. 

We may furnish a plant with carbonic acid, and all 
the materials which it may require ; we may supply 
it with humus in the most abundant quantity; but it 
will not attain complete development unless nitrogen 
is also afforded to it ; a herb will be formed, but no 
grain ; even sugar and starch may be produced but 
no gluten. 

But when we give a plant nitrogen in considera- 
ble quantity, we enable it to attract with greater en- 
ergy from the atmosphere the carbon which is neces- 
sary for its nutrition, when that in the soil is not 
sufficient ; we afford to it a means of fixing the car- 
bon of the atmosphere in its organism. 



OF URINE. 189 

We cannot ascribe much of the power of the ex- 
crements of black cattle, sheep, and horses, to the 
nitrogen which they contain, for its quantity is too 
minute. But that contained in the feeces of man is 
proportionably much greater, although by no means 
constant. In the faeces of the inhabitants of towns, 
for example, who feed on animal matter, there is 
much more of this constituent Hian in those of peas- 
ants, or of such people as reside in the country. 
The faeces of those who live principally on bread and 
potatoes are similar in composition and properties to 
those of animals. 

All excrements have in this respect a very varia- 
ble and relative value. Thus those of black cattle 
and horses are of great use on soils consisting of 
lime and sand, which contain no silicate of potash 
and phosphates; whilst their value is much less when 
applied to soils formed of argillaceous earth, basalt, 
granite, porphyry, clinkstone, and even mountain- 
limestone, because all these contain potash in con- 
siderable quantity. In such soils human excrements 
are extremely beneficial, and increase their fertility 
in a remarkable degree ; they are, of course, as ad- 
vantageous for other soils also; but for the manure 
of those first mentioned, the excrements of other 
animals are quite indispensable. 



OF URINE. 



We possess only one other natural source of ma- 
nure which acts by its nitrogen, besides the faeces 
of animals, — namely, the urine of man and animals. 

Urine is employed as a manure either in the liquid 
state, or with the faeces which are impregnated w^ith 
it. It is the urine contained in them which gives to 
the solid faeces the property of emitting ammonia, — 
a property v/hich they themselves possess only in a 
very slight degree. 

When we examine what substances we add to a 



190 OF MANURE. 

soil by supplying it with urine, we find that this 
liquid contains in solution ammoniacal salts, uric 
acid (a substance containing a large quantity of ni- 
trogen), and salts of phosphoric acid. 

According to Berzelius 1000 parts of human urine 
contain : — 

Urea 30-10 

Free Lactic acid,* Lactate of Ammonia, and animal 

matter not separable from them . . . 17.14 

Uric acid 1-00 

Mucus of the bladder 32 

Sulphate of Potash 3-71 

Sulphate of Soda 3-16 

Phosphate of Soda 2 94 

Phosphate of Ammonia ..... 1'65 

Chloride of Sodium ...... 4-45 

Muriate of Ammonia 1-50 

Phosphates of Magnesia and Lime . . . I'OO 

Siliceous earth ....... 0-03 

Water 933-UO 

1000-00 

If we subtract from the above the urea, lactate of 
ammonia, free lactic acid, uric acid, the phosphate 
and muriate of ammonia; 1 per cent, of solid matter 
remains, consisting of inorganic salts, which must 
possess the same action when brought on a field, 
whether they are dissolved in water or in urine. 
Hence the powerful influence of urine must depend 
upon its other ingredients, namely, the urea and am- 
moniacal salts. The urea in human urine exists 
partly as lactate of urea, and partly in a free state. 
(Henry.) Now when urine is allowed to putrefy 
spontaneously, that is, to pass into that state in 
which it is used as manure, all the urea in combina- 
tion with lactic acid is converted into lactate of am- 
monia, and that which was free, into volatile carbon- 
ate of ammonia. 

In dung-reservoirs well constructed and protected 
from evaporation, this carbonate of ammonia is re- 
tained in the state of solution, and when the putre- 

* Lactic acid has been found in most animal fluids and in several 
plants. It was first obtained from sour milk, hence its name from the 
Latin lac. milk. 



FIXATION OF AMMONIA. 191 

fied urine is spread over the land, a part of the am- 
monia will escape with the water which evaporates, 
but another portion will be absorbed by the soil, if 
it contains either alumina or iron; but in general 
only the muriate, phosphate, and lactate of ammonia 
remain in the ground. It is these alone, therefore, 
which enable the soil to exercise a direct influence 
on plants during the progress of their growth, and 
not a particle of them escapes being absorbed by 
the roots. 

On account of the formation of this carbonate of 
ammonia the urine becomes alkaline, although it is 
acid in its natural state. When it is lost by being 
volatilized in the air, which happens in most cases, 
the loss suffered is nearly equal to one half of the 
weight of the urine employed, so that if we fix it, 
that is, if we deprive it of its volatility, we increase 
its action twofold. The existence of carbonate of 
ammonia in putrefied urine long since suggested the 
manufacture of sal-ammoniac from this material. 
When the latter salt possessed a high price, this 
manufacture was even carried on by the farmer. For 
this purpose the liquid obtained from dunghills was 
placed in vessels of iron, and subjected to distilla- 
tion ; the product of this distillation was converted 
into muriate of ammonia by the common method. 
(Demachy.) But it is evident that such a thought- 
less proceeding must be wholly relinquished, since 
the nitrogen of 100 lbs. of sal-ammoniac (which con- 
tains 26 parts of nitrogen) is equal to the quantity 
of nitrogen contained in 1200 lbs. of the grain of 
wheat, 1480 lbs. of that of barley, or 2755 lbs. of 
hay. (Boussingault.) 

The carbonate of ammonia formed by the putrefac- 
tion of urine, can be fixed or deprived of its volatil- 
ity in many ways. 

If a field be strewed with gypsum, and then with 
putrefied urine or the drainings of dunghills, all the 
carbonate of ammonia will be converted into the sul- 
phate which will remain in the soil. 



192 OF MANURE. 

But there are still simpler means of effecting this 
purpose; — gypsum, chloride of calcium (bleaching 
salts), sulphuric or muriatic acid, and super-phos- 
phate of lime, are all substances of a very low price, 
and completely neutralize the urine, converting its 
ammonia into salts which possess no volatility. 

If a basin, filled with concentrated muriatic acid, 
is placed in a common necessary, so that its surface 
is in free communication with the vapors which rise 
from below, it becomes filled after a few days with 
crystals of muriate of ammonia. The ammonia, the 
presence of which the organs of smell amply testify, 
combines with the muriatic acid and loses entirely 
its volatility, and thick clouds or fumes of the salt 
newly formed hang over the basin. In stables the 
same may be seen. The ammonia that escapes in 
this manner is not only entirely lost, as far as our 
vegetation is concerned, but it works also a slow, 
though not less certain destruction of the walls of 
the building;. For when in contact with the lime of 
the mortar, it is converted into nitric acid, which 
gradually dissolves the lime. The injury thus done 
to a building by the formation of the soluble nitrates, 
has received (in Germany) a special name, — salpe- 
terfrass. 

The ammonia emitted from stables and necessaries 
is always in combination wnth carbonic acid. Car- 
bonate of ammonia and sulphate of lime (gypsum) 
cannot be brought together at common temperatures, 
without mutual decomposition. The ammonia enters 
into combination with the sulphuric acid, and the 
carbonic acid with the lime, forming compounds 
which are not volatile, and consequently destitute of 
all smell. Now, if we strew the floors of our stables, 
from time to time, with common gypsum, they will 
lose all their offensive smell, and none of the ammo- 
nia wdiich forms can be lost, but will be retained in 
a condition serviceable as manure. 

With the exception of urea, uric acid contains 
more nitrogen than any other substance generated 



NIGHT-SOIL. 193 

by the living organism ; it is soluble in water, and 
can be thus absorbed by the roots of plants, and its 
nitrogen assimilated in the form of ammonia, and of 
the oxalate, hydrocyanate, or carbonate of ammonia. 
It would be extremely interesting to study the 
transformations which uric acid suffers in a living 
plant. For the purpose of experiment, the plant 
should be made to grow in charcoal powder pre- 
viously heated to redness, and then mixed with pure 
uric acid. The examination of the juice of the plant, 
or of the component parts of the seed or fruit, would 
be a means of easily detecting the differences. 



NIGHT-SOIL. 



In respect to the quantity of nitrogen contained 
in excrements, 100 parts of the urine of a healthy 
man are equal to 1300 parts of the fresh dung of a 
horse, according to the analyses of Macaire and Mar- 
cet, and to 600 parts of those of a cow. Hence it 
is evident that it would be of much importance to 
agriculture if none of the human urine were lost. 
The powerful eff'ects of urine as a manure are well 
known in Flanders,* but they are considered in- 
valuable by the Chinese, who are the oldest agricul- 
tural people we know. Indeed, so much value is 
attached to the influence of human excrements by 
these people, that laws of the state forbid that any 
of them should be thrown away, and reservoirs are 
placed in every house, in which they are collected 
with the greatest care. No other kind of manure 
is used for their corn-fields, f 

* See the article " On the Agriculture of the Netherlands," Journ. 
Royal Jlgri. Soc, Vol. II. part 1, page 43, for much interesting informa- 
tion on this subject. 

t Davis, in his History of China, states that every substance con- 
vertible into manure is dilioently husbanded. " The cakes that remain 
after the expression of their vegetable oils, horns and hoofs reduced to 
powder, together with soot and ashes, and the contents of common 

17 



194 OF MANURE. 

China is the birthplace of the experimental art ; 
the incessant striving after experiments has con- 
sewers, are much used. The plaster of old kitchens, which in China 
have no chimneys but an opening at the top, is much valued ; so that 
they will sometimes put a new plaster on a kitchen for the sake of the 
old." The ammonia contained in the fuel forms nitrate of lime with 
the lime in the mortar. " All sorts of hair are used as a manure, and 
barbers' shavings are carefully appropriated to that purpose. The 
annual produce must be considerable in a country where some hundred 
millions of heads are kept constantly shaved. Dung of all animals, but 
more especially night-soil, is esteemed above all others. Being some- 
times formed into cakes, it is dried in the sun, and in this state becomes 
an object of sale to farmers, who dilute it previous to use. They con- 
struct large cisterns or pits, lined with lime plaster, as well as earthen 
tubs, sunk into the ground, with straw over them to prevent evapora- 
tion, in which all kinds of vegetables and animal refuse are collected. 
These being diluted with a sufficient quantity of liquid, are left to under- 
go the putrefactive fermentation, and then applied to the land. In the 
case of every thing except rice, the Chinese seem to manure the plant 
itself rather than the soil, supplying it copiously with their liquid 
preparation." 

"The Chinese husbandman," observes Sir G. Staunton, (Embassy, 
Vol. II.,) " always steeps the seeds he intends to sow in liquid manure, 
until they swell, and germination begins to appear, which experience 
has taught him will have the effect of hastening the growth of plants, 
as well as of defending them against the insects hidden in the ground 
in which the seeds are sown. To the roots of plants and fruit-trees, 
the Chinese farmer applies liquid manure likewise." * 

Lastly, we extract the following from a communication to Professor 
Webster, of Harvard College, United States . — " Human urine, is, if 
possible, more husbanded by the Chinese than night-soil for manure ; 
every farm, or patch of land for cultivation, has a tank, where all sub- 
stances convertible into manure are carefully deposited, the whole 
made liquid by adding urine in the proportion required, and invariably 
applied in that state." This is exactly the process followed in the 
Netherlands: see Outlines of Flemish Husbandry, page 22. 

" The business of collecting urine and night-soil employs an im- 
mense number of persons, who deposit tubs in every house in the cities 
for the reception of the urine of the inmates, which vessels are re- 
moved daily, with as much care as our farmers remove their honey from 
the hives." 

When we consider the immense value of night-soil as a manure, it is 
quite astounding that so little attention is paid to preserve it. The 
quantity is immense which is carried down by the drains in London to 
the River Thames, serving no other purpose than to pollute its waters. 
It has been shown, by a very simple calculation, that the value of 
the manure thus lost amounts annually to several millions of pounds 
sterling. A substance, which by its putrefaction generates miasmata, 
may, by artificial means, be rendered totally inoffensive, inodorous, and 
transportable, and yet prejudice prevents these means being resorted 
to. — Ed. 

* These statements are confirmed by otliers, which liave been kindly com- 
municated to me by a gentleman whose opportunities for observation during 
a residence in China of several years, were ample, and whose liberality and 
devotion to agriculture and horticulture have already conferred upon the 
community results of great interest and value. — See Appendix. 



NIGHT-SOIL. 195 

ducted the Chinese a thousand years since to dis- 
coveries, which have been the envy and admiration 
of Europeans for centuries, especially in regard to 
dyeing and painting, and to the manufactures of 
porcelain, silk, and colors for painters. These we 
were long unable to imitate, and yet they were dis- 
covered by them without the assistance of scientific 
principles ; for in the books of the Chinese we find 
recipes and directions for use, but never explanations 
of processes. 

Half a century sufficed to Europeans not only to 
equal but to surpass the Chinese in the arts and 
manufactures, and this was owing merely to the ap- 
plication of correct principles deduced from the study 
of chemistry. But how infinitely inferior is the agri- 
culture of Europe to that of China ! The Chinese 
are the most admirable gardeners and trainers of 
plants, for each of which they understand how to 
prepare and apply the best-adapted manure. The 
agriculture of their country is the most perfect in 
the world; and there, where the climate in the most 
fertile districts differs little from the European, very 
little value is attached to the excrements of animals. 
With us, thick books are w^ritten, but no experiments 
instituted : the quantity of manure consumed by this 
and that plant is expressed in hundredth parts, and 
yet we know not what manure is ! 

If we admit that the liquid and solid excrements 
of man amount on an average to l^ lb. daily (| lb. 
of urine and J lb. faeces), and that both taken to- 
gether contain 3 per cent, of nitrogen, then in one 
year they will amount to 547 lbs., which contain 
16-41 lbs. of nitrogen, a quantity sufficient to yield 
the nitrogen of 800 lbs. of wheat, rye, oats, or of 900 
lbs. of barley. (Boussingault.) 

This is much more than it is necessary to add to 
an acre of land in order to obtain, with the assistance 
of the nitrogen absorbed from the atmosphere, the 
richest possible crop every year. Every town and 
farm might thus supply itself with the manure, which. 



196 OF MANURE. 

besides containing the most nitrogen, contains also 
the most phosphates ; and if rotation of the crops 
were adopted, they would be most abundant. By 
using, at the same time, bones and the lixiviated 
ashes of wood, the excrements of animals might be 
completely dispensed with. 

When human excrements are treated in a proper 
manner, so as to remove the moisture which they 
contain without permitting the escape of ammonia, 
they may be put into such a form as will allow them 
to be transported even to great distances. 

This is already attempted in many towns, and the 
preparation of night-soil for transportation consti- 
tutes not an unimportant branch of industry. But 
the manner in which this is done is the most in- 
judicious which could be conceived. In Paris, for 
example, the excrements are preserved in the houses 
in open casks, from which they are collected and 
placed in deep pits at Montfaucon, but are not sold 
until they have attained a certain degree of dryness 
by evaporation in the air. But whilst lying in the 
receptacles appropriated for them in the houses, the 
greatest part of their urea is converted into car- 
bonate of ammonia; lactate and phosphate of am- 
monia are also formed, and the vegetable matters 
contained in them putrefy ; all their sulphates are 
decomposed, whilst their sulphur forms sulphuretted 
hydrogen and hydro-sulphate of ammonia. The mass, 
when dried by exposure to the air, has lost more 
than half of the nitrogen which the excrements 
originally contained ; for the ammonia escapes into 
the atmosphere along with the water which evapo- 
rates ; and the residue now consists principally of 
phosphate of lime, with phosphate and lactate of 
ammonia, and small quantities of urate of magnesia 
and fatty matter. Nevertheless, it is still a very 
powerful manure, but its value as such would be 
twice or four times as great, if the excrements before 
being dried were neutralized with a cheap mineral 
acid. 



NIGHT-SOIL. 197 

In other manufactories of manure the night-soil, 
whilst still soft, is mixed with the ashes of wood, or 
with earth,* both of which substances contain a large 
quantity of caustic lime, by means of which a com- 
plete expulsion of all its ammonia is eifected, and it 
is completely deprived of smell. But such a residue 
applied as manure can act only by the phosphates 
which it still contains, for all the ammoniacal salts 
have been decomposed and their ammonia expelled. 

The preparation of night-soil is now carried on 
in London to a considerable extent. Owing to the 
variable nature of the climate, artificial means are 
employed in its desiccation. The night-soil, after 
being subjected to one or other of the modes of 
treatment described below, is placed upon iron plates 
heated by means of furnaces. 

As soon as the night-soil is collected, it is placed 
in large broad trenches, until a sufficient quantity is 
accumulated for the purposes of the manufacturer. 
But here it undergoes the same process of putrefac- 
tion to which allusion has been made, and acquires a 
peculiarly offensive smell from the evolution of sul- 
phuretted hydrogen and other gases, which are 
observed to escape. Unless some means be em- 
ployed, at this stage of the process, to retain the 
ammonia, it escapes into the atmosphere in the form 
of a carbonate. Various methods have been proposed 
to effect this purpose. Some manufacturers mix the 
night-soil with chloride of lime, and evaporate off 
the water by the aid of heat. This possesses the 
advantage of depriving the excrements of smell, 
and at the same time partially fixes the ammonia 
which would otherwise escape. Chloride of lime 
always contains a considerable excess of lime; hence 
part of the ammonia contained in the night-soil is 
expelled by means of it. 

More simple and economical methods might be 
employed. A patent, which has been taken out for 

* This is practised in the vicinity of large cities in the United 
States. 

17* 



198 OF MANURE. 

the preparation of this useful manure states in its 
specification, that the night-soil is to be mixed with 
calcined mud and finely-divided charcoal. By this 
means, the smell is completely and instantaneously 
removed, and the ammonia retained by virtue of the 
affinity, whicii alumina and charcoal exert for that 
compound. This plan is both simple and efficacious, 
but the ammonia is apt to.be expelled by the appli- 
cation of the heat employed in drying the manure. 
The addition of a cheap mineral acid to the night- 
soil, before admixture with these ingredients, would 
materially improve both of the above processes. 

It would no doubt be highly advantageous in the 
preparation of manures, to prepare them so that 
they contained all the ingredients necessary for the 
supply of the plants to which they are applied. But 
these will of course vary according to the nature of 
the soils and plants for which they are intended. 
Thus bones, soap-boilers' waste, nitrate of soda, 
and ashes of wood, will often be found to form 
advantageous additions. Sulphate of magnesia (Ep- 
som salts) would, in most cases, form an invaluable 
ingredient in prepared night-soil. (See Supplemen- 
tary Chapter on Soils.) The products of the decom- 
position proceeding from the action of this salt upon 
night-soil are, sulphate of ammonia, phosphate of 
magnesia, and the double phosphate of magnesia 
and ammonia. Now all these salts exert a very 
favorable influence upon vegetation, and the phos- 
phate of magnesia is, in many cases, perfectly indis- 
pensable to the growth and development of certain 
plants. This suggestion is well worthy of the 
attention of the farmer. 

Perhaps the best and most practical method of 
fixing the ammoniacal salts of urine and night-soil, 
is to mix them with the ashes of peat or coal. When 
the latter are employed, care must be taken to select 
such as are of a porous, earthy consistence. The 
ashes both of peat and coal contain in general mag- 
nesia; hence their value as an ingredient of prepared 



GUANO. 199 

night-soil. When magnesia is not present, it will 
be necessary to add some magnesian limestone or 
Epsom salts. The night-soil should be mixed thor- 
oughly with the ashes, and exposed to the air to 
dry. The disagreeable smell is thus quickly removed, 
and a pulverulent manure obtained, which can be 
applied to the fields with facility.* 

Animal charcoal, which has served for the discol- 
oration of sugar, possesses the property of removing 
the offensive smell of night-soil, and is of itself an 
admirable manure. In cases where it can be pro- 
cured with facility, it will be found to add to the 
efficacy of the latter.f 



GUANO. 



The sterile soils of the South American coast are 
manured with a substance called guano, consisting 
of urate of ammonia and other ammoniacal salts, by 
the use of which a luxuriant vegetation and the 
richest crops are obtained. Guano has lately been 
imported in considerable quantity into Liverpool and 
several other English ports, and is now experi- 
mentally employed as a manure by English agricul- 
turists. A consideration of its composition and 
mode of action cannot, therefore, fail to be accept- 
able. 

Much speculation has arisen as to the true origin 
of Guano, J but the most certain proof is now af- 
forded, that it has been produced by the accumula- 

* Night soil deprived of its odor and rendered portable is termed 
poudrelte. One mode of preparing it, practised in France, is by boiling 
the refuse matter of slaughter-houses, by steam, into a thick soup and 
then mixing the whole into a stiff paste with sifted coal ashes, and 
drying. It is almost one half animal matter. If putrefaction should 
have begun, the addition of ashes, sweetens the whole, and the pre- 
pared "animalized coal," as it is termed, is as sweet to the nose, as 
garden mould. — Dana. 

t For an account of Mr. Daniell's artificial manure, see Appendix. 

t Much of the information regarding Guano here given is extracted 
from a paper in Liebig's Annalen, xxxvii. 3, 291. 



200 OF MANURE. 

tion of the excrements of innumerable sea-fowl, 
which inhabit the islands upon which it is found. 
Meyen, the latest writer upon this subject, completely 
coincides with this opinion; for he says* — "Their 
number is Legion ; they completely cloud the sun, 
when they r-ise from their resting-place in the morn- 
ing in flocks of miles in length." Yet, notwith- 
standing their great number, thousands of years 
must have elapsed, before the excrements could 
have accumulated to such a thickness as they pos- 
sess at present. Guano has been used by the Peru- 
vians as a manure since the twelfth century; and 
its value was considered so inestimable, that the 
government of the Incas issued a decree, by which 
capital punishment was inflicted upon any person 
found destroying the fowl on the Guano islands. 
Overseers were also appointed over each province, 
for the purpose of insuring them further protection. 
Under this state of things, the accumulation of the 
excrements may have well taken place. All these 
regulations are, however, now abandoned. f Rivero 
states, that the annual consumption of guano for the 
purposes of agriculture amounts to 40,000 fanegas. 
The increase of crops obtained by the use of guano 
is very remarkable. According to the same authority, 
the crop of potatoes is increased 45 times by means 
of it, and that of maize 35 times. The manner of 
applying the manure is singular. Thus in Arica, 
where so much pepper (^Capsicum haccatum) is cul- 
tivated, each plant is manured three times : first 
upon the appearance of "the roots, second upon that 
of the leaves, and lastly upon the formation of the 
fruit. (Humboldt.) From this it will be observed, 
that the Peruvians follow the plan of the Chinese, 
in manuring the plant rather than the soil. The 
composition of guano points out how admirably it is 
fitted for a manure ; for not only does it contain 

* Ueise um die Erde, B. i. S. 434. 

f Garcilaso, Historie de los Yncas, Vol. I. p. 134. 



GUANO. 201 

ammoniacal salts in abundance, but also those inor- 
ganic constituents which are indispensable for the 
development of plants. 

The most recent analysis is that of Volckel, who 
found it to consist of 



Urate of Ammonia 


9-0 


Oxalate of Ammonia 


10-6 


Oxalate of Lime 


70 


Phosphate of Ammonia 


60 


Phosphate of Magnesia and Ammonia 


2-6 


Sulphate of Potash .... 


5-5 


Sulphate of Soda 


3-8 


Sal-ammoniac 


4-2 


Phosphate of Lime 


143 


Clay and sand 


4-7 



Organic substances not estimated, con-^ 

taining 12 per cent, of matter insolu- (^ on.o 
ble in water. Soluble Salts of Iron C 
in small quantity. Water . . J 

lOO.O 
It will be observed from the above analysis, that 
urea does not enter into the composition of guano. 
The uric acid of the excrements must have been 
decomposed into oxalic acid and ammonia. The 
soluble substances contained in guano amount to 
half its wreight. It is singular that we do not find 
nitrates amongst the ingredients w^hich compose it. 
Guano possesses a urinous smell, precisely similar 
to that perceived on the evaporation of urine. The 
experiments upon the efficacy of this manure in 
England have not yet been sufficiently multiplied to 
enable us to judge whether or not its virtues have 
been overrated. 

The corn-fields in China receive no other manure 
than human excrements. But we cover our fields 
every year with the seeds of weeds, which from 
their nature and form pass undigested along with 
the excrements through animals, without being de- 
prived of their power of germination, and yet it is 
considered surprising that where they have once 
flourished, they cannot again be expelled by all our 
endeavors : we think it very astonishing, while we 
really sow them ourselves every year. A famous 



202 OF MANURE. 

botanist, attached to the Dutch embassy to China, 
could scarcely find a single plant on the corn-fields 
of the Chinese, except the corn itself.* 

The urine of horses contains less nitrogen and 
phosphates than that of man. According to Four- 
croy and Vauquelin it contains only five per cent, of 
solid matter, and in that quantity only 0-7 of urea; 
whilst 100 parts of the urine of man contain more 
than four times as much. 

The urine of a cow is particularly rich in salts of 
potash; but according to Rouelle and Brande, it is 
almost destitute of salts of soda. The urine of 
swine contains a large quantity of the phosphate of 
magnesia and ammonia; and hence it is that concre- 
tions of this salt are so frequently found in the 
urinary bladders of these animals. 

It is evident, that if we place the solid or liquid 
excrements of man or the liquid excrements of 
animals on our land, in equal proportion to the 
quantity of nitrogen removed from it in the form of 
plants, the sum of this element in the soil must 
increase every year; for to the quantity which we 
thus supply, another portion is added from the 
atmosphere. The nitrogen which we export as corn 
and cattle, and which is thus absorbed by large 
towns, serves only to benefit other farms, if w^e do 
not replace it. A farm which possesses no pastures, 
and not fields sufficient for the cultivation of fodder, 
requires manure containing nitrogen to be imported 
from elsewhere, if it is desired to produce a full 
crop. In large farms, the annual expenditure of 
nitrogen is completely replaced by means of the 
pastures. 

The only absolute loss of nitrogen, therefore, is 
limited to the quantity which man carries with him 
to his grave; but this at the utmost cannot amount 
to more than 3 lbs. for every individual, and is being 
collected during his whole life. Nor is this quantity 

* Ingenhouss on the Nutrition of Plants, page 129 (German edition). 



VALUE OF URINE. 203 

lost to plants, for it escapes into the atmosphere as 
ammonia during the putrefaction and decay of the 
body. 

A high degree of culture requires an increased 
supply of manure. With the abundance of the 
manure, the produce in corn and cattle will augment, 
but must diminish with its deficiency. 

From the preceding remarks it must be evident, 
that the greatest value should be attached to the 
liquid excrements of man and animals, when a ma- 
nure is desired which shall supply nitrogen to the 
soil. The greatest part of a superabundant crop, 
or, in other words, the increase of growth which is 
in our power, can be obtained exclusively by their 
means. 

When it is considered that with every pound of 
ammonia which evaporates a loss of 60 lbs. of corn 
is sustained, and that with every pound of urine a 
pound of wheat might be produced, the indifference 
with which these liquid excrements are regarded is 
quite incomprehensible. In most places only the 
solid excrements impregnated with the liquid are 
used, and the dunghills containing them are pro- 
tected neither from evaporation nor from rain. The 
solid excrements contain the insoluble, the liquid all 
the soluble phosphates, and the latter contain like- 
wise all the potash which existed as organic salts in 
the plants consumed by the animals. 

Fresh bones, wool, hair, hoofs, and horn, are ma- 
nures containing nitrogen as well as phosphates, 
and are consequently fit to aid tne process of vege- 
table life. All animal matter is fitted for the same 
purpose. Batchers' offal, such as the blood and 
intestines of animals, form a most powerful manure. 
It is in general necessary to dilute such manure by 
admixture with other kinds less powerful in their 
action. 

One hundred parts of dry bones contain from 32 
to 33 per cent, of dry gelatine ; now supposing this 
to contain the same quantity of nitrogen as animal 



204 OF MANURE. 

glue, viz., 5-28 per cent., then 100 parts of bones 
must be considered as equivalent to 250 parts of 
human urine. 

Bones may be preserved unchanged for thousands 
of years, in dry or even in moist soils, provided the 
access of rain is prevented ; as is exemplified by 
the bones of antediluvian animals found in loam or 
gypsum, the interior parts being protected by the 
exterior from the action of water. But they become 
warm when reduced to a fine powder, and moistened 
bones generate heat and enter into putrefaction; the 
gelatine which they contain is decomposed, and its 
nitroo^en converted into carbonate of ammonia and 
other ammoniacal salts, which are retained in a 
great measure by the powder itself. (Bones burnt 
till quite white, and recently heated to redness, 
absorb 7*5 times their volume of pure ammoniacal 
gas.) 



ARTIFICIAL MANURES. 

We have now examined the action of the animal 
or natural manures upon plants ; but it is evident, 
that if artificial manures contain the same constitu- 
ents, they will exercise a similar action upon the 
plants to which they are applied. We shall only 
notice here one or two of those principally employed. 

Since it has been ascertained that animal manures 
act (as far as the formation of organic matter is 
concerned) only by the ammonia which they contain, 
attention has been devoted by chemists to discover 
a more economical means of presenting this ammonia 
to plants. The water which distils from the retorts 
in the preparation of coal gas is strongly charged 
with this alkali, but is at the same time mixed with 
tar and other empyreumatic impurities. It has been 
customary to allow the tarry matter to subside, and 
decant off the clear, supernatant liquor. This liquor^ 



LIQUOR OF GAS-WORKS. 205 

being diluted to such a degree as to be tasteless, is 
applied as a manure to the field.* 

Now, the ammoniacal liquor of the gas-works con- 
tains the ammonia in the form of carbonate and 
hydro-sulphate of ammonia (sulphuret of ammonium). 
The latter compound is a deadly poison to vegeta- 
bles, nor can we conceive that by dilution its prop- 
erties can be changed. The carbonate of ammonia 
is volatile, and escapes into the atmosphere. To 
obviate this latter inconvenience and render it more 
transportable, it has been proposed to convert the 
carbonate into the sulphate, by means of gypsum, f 
But this does not remove the hydro-sulphate. A 
more simple and efScacious method is to add a solu- 
tion of sulphate of iron (the green vitriol of the shops) 
to the liquor, until no further precipitation ensues. 
Sulphuret and carbonate of iron are thus formed, 
and the whole of the ammonia enters into combina- 
tion with the sulphuric acid, and forms sulphate of 
ammonia. Care must be taken to avoid too great an 
excess of sulphate of iron ; and the liquor thus pre- 
pared should be freely exposed to the air to promote 
the oxidation. 

The liquor still, however, contains erapyreumatic 
matters, which are injurious to plants. These may 
be removed by evaporating the liquor to dryness, 
and heating the residue to incipient redness. By 
this means they are rendered insoluble, and the sul- 
phate of ammonia is not affected, unless the heat has 
been carried too far. The liquor properly diluted 
has been found very advantageous, even without the 
removal of the empyreumatic matter. 

* Mr. Blake, who has charge of the gas-work in Boston, informs me, 
that one chaldron (2700 lbs. of Pictou coal, yields, on the average, 33 
gallons of amznoniacal liquor containing about 5 per cent, of dry am- 
monia ; and by passing the gases generated from this quantity of coal 
through a solution of proto-sulphate of iron, he has obtained in addition 
24 gallons of a solution containing about 4 per cent, of dry ammonia. 
About 4 chaldrons of coal are used per diem, at the gas-works in Bos- 
ton, and 200 gallons of liquor, containing from 4 to 5 per cent, of am- 
monia, could be furnished d.iily at small cost. — W, 

i Three Lectures on Agriculture, by Dr. Daubeny, page 87. 

18 



206 OF MANURE. 

Nitrate of soda has lately engaged much attention, 
and is supposed to exert its favorable action upon 
vegetation by yielding nitrogen to those constitu- 
ents of plants which contain it. The experiments 
which have hitherto been instituted with this ma- 
nure do not warrant us in concluding with positive 
certainty that it is the nitrogen alone to which it 
owes its efficacy, but they certainly render this a 
plausible explanation of its virtues. Thus Mr. 
Pusey, the late able president of the Royal Agri- 
cultural Society, has shown, that the same effects 
are produced by putrefied urine, soot, gas-liquor, 
and nitrate of soda.* Now the three former act by 
virtue of the ammonia which enters into their com- 
position. The usual effects produced by these and 
nitrate of soda are to increase the intensity of the 
green coloring matter, to augment the quantity of 
straw, but to produce a light grain. Mr. Hyettf 
has communicated the results of an analysis of two 
samples of wheat grown under similar circumstances, 
one of which had been treated with nitre, the other 
not. The former contained 23*25 per cent, of gluten, 
and 1.375 of albumen ; the latter only 19 per cent, 
of gluten, and 0.62 of albumen. Here the azotized 
matters appear to have considerably increased in 
quantity. There is nothing opposed to the sup- 
position that nitric acid may be decomposed by 
plants, and its nitrogen assimilated. We find that 
vegetables possess the power of decomposing car- 
bonic acid, and of appropriating its carbon for their 
own use. Now this acid is infinitely more difficult 
to decompose than nitric acid. But there are other 
circumstances which oppose the adoption of the view 
that nitrate of soda acts by virtue of the nitrogen 
which enters into its composition. Were this the 
case, the action should be more uniform than it has 
hitherto been found to be. On some soils the salt 
does not possess the smallest influence; whilst on 

* Journal of the Roval Agricultural Society, Vol. II p. 123. 
t Ibid., Vol. II. p. 143. 



NITRATE OF SODA. 207 

others it affords great benefit. We can only furnish 
an explanation of this seeming caprice by a reference 
to the chemical composition of the soil upon which 
it is applied. If the advantages attending the ap- 
plication of nitrate of soda are due to the alkaline 
base which it contains, then it is evident that this 
manure can be of small value on soils containing a 
quantity of alkalies sufficient for the purposes of the 
plants grown upon them; whilst, on the other hand, 
such as are deficient in these must experience benefit 
through its means.* In certain cases in which ni- 
trate of soda has failed, nitrate of potash (common 
saltpetre) has been very successful. Analyses of 
wheat grown with nitrate of soda and nitrate of pot- 
ash would be of interest, in order to determine 
whether a mutual substitution of their respective 
bases is effected. It is to be hoped that future ex- 
periments will throw more light upon the action of 
this interesting manure, for theory cannot be satisfied 
with those already existing. It has been usual to 
employ a less quantity by weight of nitrate of pot- 
ash than of nitrate of soda. This procedure seems 
rather empirical, for unless sanctioned by experience, 
it would a priori appear to be better to add the 
greatest quantity of that salt which possesses the 
highest equivalent. Now the equivalent of nitrate of 
potash is considerably higher than that of nitrate 
of soda. 

Charcoal in a state of powder must be considered 
as a very powerful means of promoting the growth 
of plants on heavy soils, and particularly on such 
as consist of argillaceous earth, f 

* General Sir Howard Elphitistone informs me, that he found car- 
bonate of soda (soda ash) an excellent manure for his land. The crops 
obtained by means of it presented the same general characters as those 
manured witli nitrate of potash, and exhibited a greater intensity of 
color. If this is found uniformly to be the case, it will very much 
strengthen the supposition that the action of nitrate of soda is due to 
its alkaline constituent. — Ed. 

t For much valuable information on the subject of manures, see 
"Agricultural Chemistry," Vol. VIII. of Sir H. Davy's collected 
Works. 



208 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

Ingenhouss proposed dilute sulphuric acid as a 
means of increasing the fertility of a soil. Now, 
when this acid is sprinkled on calcareous soils, gyp- 
sum (sulphate of lime) is immediately formed, which 
of course prevents the necessity of manuring the 
soils with this material. 100 parts of concentrated 
sulphuric acid diluted with from 800 to 1000 parts 
of water, are equivalent to 176 parts of gypsum. 



SUPPLEMENTARY CHAPTER. 

ON THE CHEMICAL CONSTITUENTS OF SOILS. 

The fertility of a soil is much influenced by its 
physical properties, such as its porosity, color, attrac- 
tion for moisture, or state of disintegration. But 
independently of these conditions, the fertility de- 
pends upon the chemical constituents of which the 
soil is composed. 

We have already shown, at considerable length, 
that those alkalies, earths, and phosphates, which 
constitute the ashes of plants, are perfectly indis- 
pensable for their development ; and that plants 
cannot flourish upon soils from which these com- 
pounds are absent. The necessity of alkalies for 
the vital processes of plants will be obvious, when 
we consider that almost all the different families of 
plants are distinguished by containing certain acids, 
differing very much in composition ; and further, 
that these acids do not exist in the juice in an 
isolated state, but generally in combination with 
certain alkaline or earthy bases. The juice of the 
vine contains tartaric acid, that of the sorrel oxalic 
acid. It is quite obvious, that a peculiar action must 
be in operation in the organism of the vine and 
sorrel, by means of which the generation of tartaric 
and oxalic acid is effected ; and also that the same 
action must exist in all plants of the same genus. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 209 

A similar cause forces corn-plants to extract silicic 
acid from the soil. The number of acids found 
in different plants is very numerous, but the most 
common are those which we have already mentioned; 
to which may be added acetic, malic, citric, aconitic, 
raaleic, kinovic acids, &c. 

When we observe that the proper acids of each 
family of plants are never absent from it, we must 
admit that the plants belonging to that family could 
not attain perfection, if the generation of their 
peculiar acids were prevented. Hence, if the pro- 
duction of tartaric acid in the vine were rendered 
impossible, it could not produce grapes, or in other 
words, would not fructify. Now the generation of 
organic acids is prevented in the vine, and, indeed, 
in all plants which yield nourishment to men and 
animals, when alkalies are absent from the soil in 
which they grow. The organic acids in plants are 
very rarely found in a free state ; in general, they 
are in combination with potash, soda, lime, or mag- 
nesia. Thus, silicic acid is found as silicate of 
potash, acetic acid as acetate of potash or soda, 
oxalic acid as oxalate of potash, soda, or lime, tar- 
taric acid as bitartrate of potash, &c. The potash, 
soda, lime, and magnesia in these plants are, there- 
fore, as indispensable for their existence as the 
carbon from which their organic acids are produced. 

In order not to form an erroneous conclusion re- 
garding the processes of vegetable nutrition, it must 
be admitted that plants require certain salts for the 
sustenance of their vital functions, the acids of 
which salts exist either in the soil (such as silicic or 
phosphoric acids) or are generated from nutriment 
derived from the atmosphere. Hence, if these salts 
are not contained in the soil, or if the bases neces- 
sary for their production be absent, they cannot be 
formed; or in other words, plants cannot grow in 
such a soil. The juice, fruit, and leaves of a plant 
cannot attain maturity, if the constituents necessary 
for their formation are wanting, and salts must be 
18* 



210 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

viewed as such. These salts do not, however, occur 
simultaneously in all plants. Thus, in saline plants, 
soda is the only alkali found ; in corn plants, lime 
and potash form constituents. Several contain both 
soda and potash, some both potash and lime ; whilst 
others contain potash and magnesia. The acids 
vary in a similar manner. Thus one plant may 
contain phosphate of lime, a second, phosphate of 
magnesia, a third, an alkali combined with silicic 
acid, and a fourth, an alkali in combination with a 
vegetable acid. The respective quantities of the 
salts required by plants are very unequal. The 
aptitude of a soil to produce one, but not another 
kind of plant, is due to the presence of a base which 
the former requires, and the absence of that, indis- 
pensable for the development, of the latter. Upon 
the correct knowledge of the bases and salts requi- 
site for the sustenance of each plant, and of the 
composition of the soil upon which it grows, depends 
the whole system of a rational theory of agriculture; 
and that knowledge alone can explain the process 
of fallow, or furnish us with the most advantageous 
methods of affording plants their proper nourish- 
ment. 

Give, — so says the rational theory, — to one plant 
such substances as are necessary for its development, 
but spare those, which are not requisite, for the 
production of other plants that require them. 

It is the same with regard to these bases as it is 
with the water which is necessary for the roots of 
various plants. Thus, whilst one plant flourishes 
luxuriantly in an arid soil, a second requires much 
moisture, a third finds necessary this moisture at 
the commencement of its development, and a fourth 
(such as potatoes) after the appearance of the blos- 
som. It would be very erroneous to present the 
same quantity of water to all plants indiscriminately. 
Yet this obvious principle is lost sight of in the 
manuring of plants. An empirical system of agri- 
culture has administered the same kind of manures 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 211 

to all plants; or when a selection has been made, it 
was not based upon a knowledge of their peculiar 
characters or composition. 

The cost of labor in England has given rise to 
the production of much ingenuity in the invention 
of machines, which have produced improvements in 
the mode of application of manures. In order to 
use these with advantage, pulverulent manures are 
employed, instead of the common stable manure, 
which is generally mixed with much straw. 

The necessity for such forms of manure naturally 
suggested the employment of bone dust, dried dung, 
lime, ashes, &c. Now, although by these means the 
necessary phosphates are furnished to a soil, and 
solid animal excrements rendered unnecessary, they 
have led to the neglect of the liquid excrements, 
that is, of the urine of men and animals, which is 
thus completely lost to agriculture. For although 
the meadows receive, during autumn and winter, 
when cattle are fed upon them, the solid and liquid 
excrements of these animals, yet the urine of man, 
into which all the nitrogenous constituents of ani- 
mals are finally deposited, is completely lost to the 
fields. This most important of all manures, so pro- 
perly estimated in Flanders, Germany, and China, is 
altogether lost to the English agriculturist. In large 
towns it is either allowed to run into the rivers, or 
sink into the ground in such a manner as to be of no 
benefit to the veg-etable kingdom. 

The most important growth in England is that of 
wheat; then of barley, oats, beans, and turnips. Po- 
tatoes are only cultivated to a great extent in certain 
localities ; rye, beet-root, and rape-seed, not very 
generally. Lucern is only known in a few districts, 
whilst red clover is found universally. Now, the se- 
lection of inorganic manures for these plants may be 
fixed upon by an examination of the coniposition of 
their ashes. Thus wheat must be cultivated in a soil 
rich in silicate of potash. If this soil is formed from 
feldspar, mica, basalt, clinkstone, or indeed of any 



212 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

minerals which disintegrate with facility, crops of 
wheat and barley may be grown upon it for many 
centuries in succession. But, in order to support an 
uninterrupted succession, the annual disintegration 
must be sufficiently great to render soluble a quanti- 
ty of silicate of potash sufficient for the supply of a 
full crop of wheat or barley. If this is not the case, 
the soil must either be allowed to lie fallow from 
time to time, or plants may be cultivated upon it 
which contain little silicate of potash, or the roots 
of which are enabled to penetrate deeper into the 
soil than corn plants in search of this salt. During 
this interval of repose, the materials of the soil dis- 
integrate, and potash in a soluble state is liberated 
on the layers exposed to the action of the atmo- 
sphere. When this has taken place, rich crops of 
wheat may be again expected. 

The alkaline phosphates, as well as the phosphates 
of magnesia and lime, are necessary for the produc- 
tion of all corn-plants. Now, bones contain the latter, 
but none of the former salts. These must, therefore, 
be furnished by means of night-soil, or of urine, a 
manure which is particularly rich in them.* Wood 
ashes have been found very useful for wheat in cal- 
careous soils ; for these ashes contain both phos- 
phate of lime and silicate of potash. In like man- 
ner stable manure and night-soil render clayey soils 
fertile, by furnishing the magnesia in which they are 
deficient. The ashes of all kinds of herbs and de- 
cayed straw are capable of replacing wood ashes. 

A compost manure, which is adapted to furnish all 
the inorganic matters to wheat, oats, and barley, may 
be made, by mixing equal parts of bone dust and a 
solution of silicate of potash (known as soluble glass 
in commerce), allowing this mixture to dry in the 
air, and then adding 10 or 12 parts of gypsum, with 
16 parts of common salt. Such a compost would 

* It has been already stated that bran contains phosphate of soda and 
phosphate of magnesia, so that it is useful as a manure where phos- 
phates are desired. — Ed. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 213 

render unnecessary the animal manures, which act 
by their inorganic ingredients. According to Ber- 
thier, 100 jDarts of the ashes of wheat straw con- 
tain, — 

Of matter soluble in water ..... 9-0 
Of matter insoluble in water .... 91-0 

Now 100 parts of the soluble matter contain, — 

Carbonic acid ...... a trace 

Sulphuric acid ....... 20 

Muriatic acid ....... 130 

Silica 350 

Potash and Soda 500 

1000 
100 parts of the insoluble matter contain, — 

Carbonic acid . . . . .0 

Phosphoric acid . . . . .1-2 

Silica 750 

Lime ...... 5'8 

Oxide of Iron and Charcoal .... 10-0 

Potash 8-0 

100-0 
The silicate of potash employed in the preparation 
of the compost described above must not deliquesce 
on exposure to the air, but must give a gelatinous 
consistence to the water in which it is dissolved, and 
dry to a white powder by exposure. It is only at- 
tractive of moisture when an excess of potash is 
present, which is apt to exert an injurious influence 
upon the tender roots of plants. In those cases 
where silicate of potash cannot be procured, a suflEi- 
ciency of wood ashes will supply its place.* 

All culinary vegetables, but particularly the cruci- 



* In some parts of the grand duchy of Hesse, where wood is scarce 
and dear, it is customary for the common people to club together and 
build baking ovens, which are heated with straw instead of wood. The 
ashes of this straw are carefully collected and sold every year at very 
high prices. The farmers there have found by experience that the 
ashes of straw form the very best manure for wheat; although it exerts 
no influence on the growth of fallow-crops (potatoes or the leguminosa?, 
for example). The stem of wheat grown in this way possesses an un- 
common strength. The cause of the favorable action of these ashes 
will be apparent, when it is considered that all corn- plants require sili- 
cate of potash ; and that the ashes of straw consist almost entirely of 
this compound. — Ed. 



214 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

feree, such as mustard, {^sinapis alba and nigra,) con- 
tain sulphur in notable quantity. The same is the 
case with turnips, the different varieties of rape, cab- 
bage, celery, and red clover. These plants thrive 
best in soils containing sulphates ; hence if these 
salts do not form natural constituents of the soil, 
they must be introduced as manure. Sulphate of 
ammonia is the best salt for this purpose. It is most 
easily procured by the addition of gypsum or sul- 
phate of iron* (green vitriol) to putrefied urine. 

Horn, wool, and hoofs of cattle, contain sulphur 
as a constituent, so that they will be found a valua- 
ble manure when administered with soluble phos- 
phates, (with urine, for example.) 

Phosphate of magnesia and ammonia forms the 
principal inorganic constituent of the potato ; salts 
of potash also exist in it, but in very limited quanti- 
ty. Now the soil is rendered unfitted for its culti- 
vation, even though the herb be returned to it after 
the removal of the crop, unless some means are 
adopted to replace the phosphate of magnesia re- 
moved in the bulbous roots. This is best effected 
by mixtures of night-soil with bran, magnesian lime- 
stone, or the ashes of certain kinds of coal. I ap- 
plied to a field of potatoes manure, consisting of 
night-soil and sulphate of magnesia (Epsom salts), 
and obtained a remarkably large crop. The manure 
was prepared by adding a quantity of sulphate of 
magnesia to a mixture of urine and feeces, and mix- 
ing the whole with the ashes of coal or vegetable 
mould, till it acquired the consistence of a thick 
paste, which was thus dried by exposure to the sun. 

It has been formerly mentioned, that the seconda- 
ry and tertiary limestones contain potash : marl, and 
the calcareous minerals used for the preparation of 
hydraulic mortar, may be particularly specified. 

* If sulphate of iron be employed, it ought not to be added in great 
excess, and the urine must be exposed to the air for some time after, 
for the purpose of converting the iron into the peroxide. A salt of the 
protoxide of iron is injurious to vegetation. — Ed. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 215 

These Lave been found to form excellent manures 
for heavy clayey soils, particularly for such as disin- 
tegrate with difficulty. They are most efficacious 
when burnt, but can only be applied in this state 
after harvest, and ought to be ploughed into the soil 
as quickly as possible. By the action of lime upon 
clay, the potash contained in the latter is rendered 
soluble. This may easily be shown by mixing one 
part of marl with half its weight of burned lime, 
adding \vater, and setting aside the mixture to re- 
pose for some time. Even after a space of 24 hours, 
an appreciable quantity of potash may be detected 
in the water.* 

A most striking proof of the influence of potash 
upon vegetation has been furnished by the investi- 
gations of the " admiiiistration " of tobacco in Paris. 
For many years accurate analyses of the ashes of 
various sorts of tobacco have been executed, by the 
, orders of the " administration " ; and it has been 
I found, as the result of these, that the value of the 
I tobacco stands in a certain relation to the quantity 
of potash contained in the ashes. By this means a 
' mode was furnished of distinguishing the different 
i soils upon which the tobacco under examination had 
i been cultivated, as well as the peculiar class to 
I which it belonged. Another striking fact was also 
, disclosed through these analyses. Certain cele- 
brated kinds of American tobacco were found gradu- 
1 ally to yield a smaller quantity of ashes, and their 
I value diminished in the same proportion. For this 
j information I am indebted to M. Pelouze, professor 
., of the Polytechnic School in Paris. 

!• One of the causes of the advantages produced by subsoil ploughing 
is, that it exposes the soil to the disintegrating influences of the atmo- 
; sphere. Hence it is that the subsoil plough is so beneficial in siliceous 
M soils, and exerts no apparent eifect upon those which contain much 

I clay. The former disintegrate and liberate their potash both with fa- 
|J cility and rapidity ; whilst the disintegration of the latter proceeds with 

II slowness, and no appreciable effects are produced. (See Journal of the 
']. Agricultural Society, Vol. II. p. 27;) It is probable however, that if 
'the land received a dressing of lime after subsoil ploughing, the effects 

would be produced more rapidly. — Ed. 



216 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

There are certain plants which contain either no 
potash, or mere traces of it. Such are the poppy, 
\papave7' soinniferuni,) which generates in its organ- 
ism a vegetable alkaloid; Indian corn (^zea mays); 
and kelianthus tuberosus. For plants such as these 
the potash in the soil is of no use, and farmers are 
well aware that they can be cultivated without ro- 
tation on the same soil, particularly when the herbs 
and straw, or their ashes, are returned to the soil 
after the reaping of the crop. 

One cause of the favorable action of the nitrates 
of soda and potash must doubtless be, that through 
their agency the akalies which are deficient in a soil 
are furnished to it. Thus it has been found that in 
soils deficient in potash, the nitrates of soda or pot- 
ash have been very advantageous ; whilst those, on 
the other hand, which contain a sufficiency of alka- 
lies, have experienced no beneficial effects through i 
their means. In the application of manures to soils 
we should be guided by the general composition of 
the ashes of plants, whilst the manure applied to a 
particular plant ought to be selected with reference 
to the substances which it demands for its nourish- 
ment. In general, a manure should contain a large 
quantity of alkaline salts, a considerable proportion 
of phosphate of magnesia, and a smaller proportion 
of phosphate of lime; azotized manure and ammonia- 
cal salts cannot be too frequently employed. 

In the following part of this chapter I shall de- 
scribe a number of analyses of soils executed by 
Sprengel, together with observations on their sterili- 
ty and fertility, as stated by that distinguished 
agriculturist. It is unnecessary to describe the Wio- 
rfws operandi used in the analyses of these soils, for 
this kind of research will never be made by farmers, 
who must apply to the professional chemist, if they 
wish for information regarding the composition of 
their soils. 

Under the term surface-soil, we mean that portion 
of soil which is on the surface ; whilst by subsoil we( 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 217 

mean that which is below the former, and out of 
reach of the ordinary plough. 



CHEMICAL COMPOSITION OF CERTAIN SOILS, ACCORDING TO 
ANALYSIS. 

1. Surface-soil (A) a good loamy soil, from the 
vicinity of Gandersheim. It is remarkable for pro- 
ducing uncommonly fine red clover when manured 
with gypsum. (B) is an analysis of the subsoil. 
100 parts contain : — 

Silica, with fine siliceous sand 
Alumina ...... 

Peroxide of iron, with "a little protoxide 

Peroxide of manganese 

Magnesia and silica, in combination with 

sulphuric acid and humus . 
Magnesia, with silica and humic acid 

combined ..... 

Potash, in combination with silica 
Soda, principally in combination with 

silica, and a little as common salt 
Phosphoric acid ..... 
Sulphuric acid in combination with lime O-lll 

Ciilorine (in common salt) . . ~ 

Humus, with traces of azotized matter 

100-000 100-000 

An inspection of the above analyses will show 
that the soil contains a very small proportion of salts 
of sulphuric acid, — a circumstance which accounts 
for the favorable action of gyps4im upon it. 

2. The surface-soil (A) is a fine-grained loamy 
soil from Gandersheim, distinguished for the re- 
markably large crops of beans, peas, tares, &c., 
which it produces when manured with gypsum. (B) 
is the analysis of the subsoil. 100 parts contain : — 



(A) 
. 91-331 
1-344 
1562 

. 0-082 


(B) 
93-883 
1-944 
2226 
0-320 


. 0-800 


0720 


0-440 
. 0156 


0-340 
0-105 


. 0-066 
0-098 

3ie 0111 
0012 

. 4100 


0-060 
0-190 
0-012 
0012 
0-184 





(A) 


(B) 


Silica, with fine siliceous sand 


. 90-221 


92-324 


Alumina 


2-106 


2262 


Peroxide and protoxide of iron 


. 3951 


2914 


Peroxide of manganese 


0-960 


2-960 


Lime, principally combined with phos- 






phoric acid and humus . 


0539 


0-532 


19 







218 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Magnesia, with silicate of potash, &c. 

Potash 

Soda ...... 

Phosphoric acid ..... 

Sulphuric acid (in gypsum) . 
Chlorine (in commor. salt) 
Humus and azotized matter . 
Loss 



(A) 


(B) 


0-780 


0-340 


0-066 


0-304 


0-010 


a trace 


0-367 


01 -22 


a trace 


0010 


OIUO 


0004 


0900 




0140 


0-228 


100-000 


100000 



The analysis of this soil shows, that, with the ex- 
ception of gypsjim, every ingredient is present 
which is requisite for the nourishment of leguminous 
plants. Hence it is that gypsum exerts such a 
favorable influence upon it. 

3. Surface-soil (A) a stro 
Brunswick. (B) the analysi: 
parts contain : — 

Silica, with coarse siliceous sand 

Alumina 

Peroxide and protoxide of iron 
Peroxide of manganese 

Lime 

Magnesia .... 

Potash and soda, the greatest part in 

combination with silica 
Phosphate of iron 
Sulphuric acid (in gypsum) . 
Chlorine (in common salt) 
Humus .... 



Damy 


sand, from 


the subsoil. 100 


(A) 


(B) 


95-698 


96-880 


0-504 


0-890 


2496 


1-496 


a trace 


a trace 


0038 


0-019 


0-147 


0-260 


0-090 


0-079 


0-164 


0110 


0007 


a trace 


0-010 


a trace 


0-846 


0-226 



100000 100-000 
This soil was much improved by manuring with 
lime and ashes. It was then found well fitted for 
clover, beans, and peas. 

4. Surface-soil (A) a loamy sand, from the envi- 
rons of Brunswick. (B) analysis of the subsoil at 
the depth of 3 feet. 100 parts contain: — 

(A) (B) 

Silica and fine siliceous sand . . 94-724 97-340 

Alumina . . . . 1-638 0-806 

Protoxide and peroxide of iron with man- 
ganese ..... 1-960 1201 

Lime 1-028 0-296 

Maornesia . . . .a trace 0095 

Potash and soda . . . 0077 0-112 

Phosphoric acid .... 0-024 0-015 

Gypsum .... 0.010 a trace 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 219 



(A) (B) 

Chlorine of the salt . . . 0'207 a trace 

Humus .... 0-512 0U5 



100-000 100-000 

This soil produces luxuriant crops of lucern and 
sainfoin, as well as of all other plants the roots of 
which penetrate deeply into the ground. The rea- 
son is apparent. The subsoil contains magnesia, 
which is wanting in the surface-soil. 

5. Surface-soil (A) a loamy sand, from the envi- 
rons of Brunswick. (B) analysis of the subsoil at a 
depth of 2 feet. 100 parts contain : — 

Silica, with coarse siliceous sand 

Alumina .... 

Protoxide and peroxide of iron . 

Peroxide of manganese 

Lime, in combination with silica 

Magnesia in do. do. 

Potash and soda . 

Phosphate of iron . . 

Sulphuric acid 

Chlorine 

Humus soluble in alkalies 

Humus insoluble in alkalies . 

100-000 100-000 

This soil is characterized by its great sterility. 
White clover could not be made to grow upon it. 
The obvious cause of its poverty is a deficiency of 
lime, magnesia, potash, and gypsum ; for we find 
that the fertility of the soil was much increased by 
manuring it with marl. The white clover, which 
formerly had refused to grow on this soil, now grew 
upon it with much luxuriance. The aridity of the 
soil could not have been the cause of its sterility, 
for the stiff nature of the subsoil on which it rested 
prevented a deficiency of moisture. 

6. Surface-soil (A) a loamy land from the environs 
of Brunswick. (B) the analysis of the subsoil, at a 
depth of 2 feet. 100 parts contain: — 



(A) 


(B) 


. 95-843 


95-180 


600 


1-600 


. 1-800 


2-200 


a trace 


a trace 


. 0038 


0-455 


0006 


0-160 


. 0-005 


0004 


0198 


400 


. 0-002 


a trace 


0-006 


0001 


. 1-000 


. . • 


0-502 


• • • 





(A) 


(B) 


Silica, with fine siliceous sand . 


. 94-998 


96-490 


Alumina 


0610 


1-083 


Protoxide and peroxide of iron . 


. 1080 


1-472 



220 ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Peroxide of manganese 

Lime, in combination with silica 

Magnesia, idem 

Potash, idem ... 

Soda, idern .... 

Phosphate of iron 

Gypsum .... 

Common salt ... 

Humus soluble in alkalies 

Humus accompanied by azotized matter 

Resinous matter 



(A) 


(B) 


0-2(J8 


0-400 


0141 


0-182 


0-208 


0-205 


. 0050 


0-070 


0044 


0-050 


008G 


0030 


0041 


0005 


. 0-004 


0-003 


0-400 


0010 


2070 


. . . 


a trace 




100000 


100000 



This soil is by no means remarkable for its steril- 
ity, but is decidedly improved by manuring with 
burned ferruginous loam. It is, however, rendered 
still better by the use of burned marl, — a manure 
which is rich in iron, potash, gypsum, and phosphate 
of lime. The marl does not exert so favorable an 
action when applied in its natural state ; but the heat 
liberates the potash from the insoluble compound 
which it forms with silica. 

7. Surface-soil (A) a loamy sand, from Brunswick. 
(B) analysis of the subsoil at a depth of 1| feet. 100 
parts contain : — 





(A) 


(B) 


Silica, with fine siliceous sand . 


. 92 980 


96-414 


Alumina .... 


820 


1-000 


Protoxide and peroxide of iron . 


. 1-666 


1-370 


Peroxide of manganese 


0-188 


0-240 


Lime, combined with silica 


. 0748 


0-364 


Magnesia, idem 


0-1C8 


0160 


Potash, idejii 


. 0065 


0045 


Soda, idem .... 


0-130 


0082 


Phosphate of iron 


. 0246 


043 


Sulphuric acid contained in gypsum 


a trace 


0005 


Chlorine .... 


. a trace 


0-007 


Humus soluble in alkalies 


0764 


0270 


Humus, with azotized organic remains 


2225 





100-000 100-000 

This soil when manured with gypsum is very fa- 
vorable to the production of leguminous plants and 
red clover. But it is very remarkable, on account of 
the rust which always attacks the corn plants which 
may be grown upon it. This rust and mildew {tiredo 
linearis, pucdnia graminis) is a disease which at- 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



221 



tacks the stem and leaves, and is quite different from 
the brand [iiredo glumai'um) which appears on the 
seeds and organs of reproduction. Rust is most fre- 
quently detected on plants growing on soils which 
contain bog-ore, or turf iron-ore. According to 
Sprengel, rust contains phosphate of iron, to which 
this chemist ascribes the origin of the disease. It 
is very possible that other causes may operate in the 
production of similar diseases. 

8. Soil, a fine-grained loamy marl, from the vicin- 
ity of Schoningen. It produces corn, which is, how- 
ever, very liable to blight. 100 parts contain : — 



Silica, with siliceous sand . 


. 93-870 


Alumina .... 


1-248 


Protoxide and peroxide of iron 


. 1-418 


Peroxide of manganese . 


0-360 


Lime (principally carbonate) 


. 0-546 


Magnesia, idem, .... 


0560 


Potash, with silica . . . . 


. 0-050 


Soda, with silica 


0040 


Phosphate of iron . . . , 


. 0-246 


Sulphuric acid with lime 


0-027 


Carbonic acid, with lime and magnesia 


. 1-145 


Humus soluble in alkalies 


0-400 


Humus . . . . . 


. 0-090 



100-000 

It will be observed that a considerable quantity of 
phosphate of iron is contained in this soil, and the 
corn which grows upon it is, as in the former case, 
disposed to rust. 

9. Surface-soil (A) a loamy soil, from Brunswick, 
remarkable on account of producing buck-wheat, 
which is exceedingly poor in the grain. (B) analy- 
sis of the subsoil at a depth of 1| foot. 100 parts 
contain : — 



Silica, with coarse siliceous sand 
Alumina .... 

Protoxide and peroxide of iron 
Protoxide and peroxide of manganese 
Lime, in combination with silica 
Magnesia, idem 

Potash, with silica . . 

Soda ..... 
Phosphate of iron 
Sulphuric acid with lime 

19* 



(A) 


(B) 


95-114 


92-458 


1080 


2-530 


1-900 


2 502 


0-320 


920 


380 


0-710 


0300 


0-551 


0020 


0120 


0004 


0-034 


0052 


0175 


0-006 


a trace 



222 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Chlorine (in common salt) 
Humus soluble in alkalies 
Humus 



(A) (B) 

0.005 a trace 

0-619 . . . 

0200 . . . 



100-000 100000 



By manuring the land with wood ashes, the soil is 
enabled to produce buck-wheat, with rich grain ; the 
leguminous plants also thrive luxuriantly upon it. 
This increased fertility is due to the ashes, by means 
of which both potash and phosphates are supplied to 
the land. 

10. Subsoil of a loamy, sandy soil, from Brunswick. 
It is remarkable for having produced excellent crops 
of hops for a long series of years. 100 parts, by 
weight, consist of: — 



Silica, with siliceous sand 


95-660 


Alumina 


. 1-586 


Protoxide and peroxide of iron 


1-616 


Peroxide of manganese 


. 0-240 


Lime, in combination with silica 


0-083 


Magnesia 


. 0080 


Potash .... 


OO.'iO 


Soda .... 


. 0-220 


Phosphoric acid 


0039 


Sulphuric acid 


, 0-003 


Chlorine .... 


a trace 


Humus soluble in alkalies 


. 0-080 


Humus .... 


0-360 



100000 

Although the hops contain a large quantity of 
potash, soda, phosphoric acid, sulphuric acid, lime, 
and magnesia, yet we do not find that these exist 
in the soil in superabundant quantity. Nor is it 
necessary that they should, for the roots of the hops 
penetrate 8 or 10 feet deep into the soil, and search 
out the materials fitted to nourish the plants. Hence 
it is that hops thrive well on soils comparatively 
poor in their proper ingredients. The same is the 
case with all plants of a similar nature, the roots of 
which possess a tendency to extend in search of 
food; we see this particularly in lucern and sainfoin. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 223 



SOILS OF HEATHS. 

11. Soil of a heath converted into arable land, in 
the vicinity of Brunswick. It is naturally sterile, 
but produces good crops when manured with lime, 
marl, cow-dung, or the ashes of the heaths which 
grow upon it. 

Silica, and coarse siliceous sand . . 71 -504 
Alumina ..... 0780 
Protoxide and peroxide of iron, principally com- 
bined with humus . . . 0420 
Peroxide of manganese, idem . . , 0'220 
Lime, idein .... 0*J34 
Magnesia, idem ..... 0032 
Potash and soda principally as silicates . 0'058 
Phosphoric acid, (principally as phosphate of iron) 0-115 
Sulphuric acid (in gypsum) . . . O'OIS 
Chlorine (in common salt) . . . 0-014 
Humus soluble in alkalies . . . 9 820 
Humus, with vegetable remains . . 14-975 
Resinous matters .... 1'910 

100000 

Ashes of the soil of the heath, before being con- 
verted into arable land: — 

Silica, with siliceous sand . . . 92'641 
Alumina ..... 1-352 
Oxides of iron and manganese . . 2.324 
Lime, in combination with sulphuric and phos- 
phoric acids ..... 0-929 
Magnesia, combined with sulphuric acid . 0-283 
Potash and soda (principally as sulphates and 

phosphates) ..... 0-564 

Phosphoric acid, combined with lime . 250 

Sulphuric acid, with potash, soda, and lime . 1-G20 

Chlorine in common salt . . . 0-037 



100.000 
12. Surface-soil of a fine-grained loam, from the 
vicinity of Brunswick. It is remarkable from the 
circumstance, that not a single year passes in which 
corn plants are cultivated upon it without the stem 
of the plants being attacked by rust. Even the 
grain is covered with a yellow rust, and is much 
shrunk. 100 parts of the soil contain: — 

Silica and fine siliceous sand . . 87 859 

Alumina ..... 2652 

Peroxide of iron with a large proportion of protoxide 5- 132 



224 ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Protoxide and peroxide of manganese . 0"840 

Lime principally combined with silica . . 1-459 

Magnesia idevi .... 0-280 

Potash and soda idem .... O-OiiQ 

Phosphoric acid in combination with iron . 0-505 

Sulphuric acid in combination with lime . 0"068 

Chlorine in common salt . . . 0-006 

Humus . . ... 1-109 



100-000 
This soil does not suffer from want of drainage : 
it is well exposed to the sun, is in an elevated situa- 
tion, and in a good state of cultivation. In order 
to ascertain whether the rust was due to the con- 
stituents of the soil, (phosphate of iron ?) or to cer- 
tain fortuitous circumstances unconnected with their 
operation, a portion of the land was removed to 
another locality, and made into an artificial soil of 
fifteen inches in depth. Upon this barley and wheat 
were sown ; but it was found, as in the former case, 
that the plants were attacked by rust, whilst barley 
growing on the land surrounding this soil was not 
at all affected by the disease. From this experiment 
it follows, that certain constituents in the soil favor 
the development of rust. 

13. Soil of a heath, which had been brought into 
cultivation in the vicinity of Brunswick. The analy- 
sis was made before any kind of crops had been 
grown upon it. Corn-plants were first reared upon 
the new soil, but were found to be attacked by rust, 
even on those parts which had been manured respec- 
tively with lime, marl, potash, wood ashes, bone-dust, 
ashes of the heath plant, common salt, and ammonia. 
100 parts contain: — 

Silica with coarse siliceous sand . . 51.337 

Alumina ..... 0528 
Protoxide and peroxide of iron in combination 

with phosphoric and humic acids . . 0-398 

Protoxide and peroxide of manganese . . 005 

Lime in combination with humus . . 0-230 

Magnesia idem ..... 0-040 

Potash and soda .... 0-010 

Phosphoric acid .... 0066 

Sulphuric acid .... 0-022 

Chlorine ..... 0-O14 

Humus soluble in alkalies . . . 13210 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 225 

Resinous matters . . . , 2-040 

Coal of humus and water . . . 32-100 



100000 



The next analysis represents the soil after being 
burnt. 100 parts by weight of the soil left after 
ignition only 50 parts. 100 parts of these ashes 
consisted of: — 

Silica and siliceous sand . . . 95-204 

Alumina ..... 1-640 

Peroxide of iron .... 1-344 

Peroxide of manganese .... 0080 

Lime in combination with sulphuric acid . 0-544 

Magnesia combined with silica . . 0-465 

Potash and soda .... 052 

Phosphoric acid (principally as phosphate of iron) 330 

Sulphuric acid . . . . 322 

Chlorine ..... 0019 



100-000 
By comparing this analysis with the one which 
has preceded it, an increase in certain of the con- 
stituents is observed, particularly with respect to 
the sulphuric acid, potash, soda, magnesia, oxide of 
iron, oxide of manganese, and alumina. From this 
it follows, that the humus, or in other words, the 
vegetable remains, must have contained a quantity 
of these substances confined within it, in such a 
manner that they were not exhibited by analysis. 

Oats and barley were sown on this land the 
second year after being reclaimed, and both suffered 
much from rust, although different parts of the soil 
were manured with marl, lime, and peat-ashes^ whilst 
other portions were left without manure. In the 
first year, all the different parts of the field pro- 
duced potatoes, but they succeeded best in those 
divisions which had been manured with peat-ashes, 
lime and marl. In the second year, oats mixed with 
a little barley were sown upon the soil ; and the 
straw was found to be strongest on the parts treated 
with peat-ashes, lime, marl, and ashes of wood. Red 
clover was sown on the third year ; it appeared in 
best condition on those portions of the soil manured 
with marl and lime. Upon the divisions of the field 



226 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

■which had been left without manure, as well as on 
those manured with bone-dust, potash, ammonia, and 
common salt, the clover scarcely appeared above 
ground. The divisions of the field, which had been 
manured in the first year with peat-ashes, ammonia, 
and ashes of wood, were sown with buckwheat after 
the removal of the first crop of clover. The buck- 
wheat succeeded very well on all the divisions, yet 
a marked difference was perceptible in favor of the 
portion treated with ammonia. These experiments 
show us, that a dressing of lime did not completely 
remove from the soil its tendency to impart rust to 
the plants grown upon it. Nevertheless it is highly 
probable, that as soon as the protoxide of iron 
became converted into the peroxide by exposure to 
the atmosphere, lime would possess more power in 
decomposing the phosphate of iron. 

14. Subsoil of a loamy soil in the vicinity of 
Brunswick. It is remarkable from the circumstance 
that sainfoin cannot be cultivated upon it more than 
two or three years in succession. The portion 
analyzed was taken from a depth of five feet. 100 
parts contained: — 

Silica with very fine siliceous sand . . 90-035 

Alumina ..... 1-976 

Peroxide of iron .... 4 700 

Protoxide of iron . . . ,1115 

Protoxide and peroxide of manganese . 0240 

Lime ...... 0022 

Magnesia ..... O-llS 

Potash and soda • . . . 300 

Phosphoric acid, combined with iron . . 0098 

Sulphuric acid (the greatest part in combination 

with protoxide of iron) . . . 1-39J 

Chlorine . , , . .a trace 



100000 



Now the results of the analysis give a suflflcient 
account of the failure of the sainfoin. The soil 
contains above one per cent. of. sulphate of the pro- 
toxide of iron {green vitriol of commerce), a salt 
which exerts a poisonous action upon plants. Lime 
is not present in quantity suflScient to decompose 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 227 

this salt. Hence it is that sainfoin will not thrive 
on this soil, nor indeed lucern, or any other of the 
plants with deep roots. The evil cannot be obviated 
by any methods sufficiently economical for the far- 
mer, because the soil cannot be mixed with lime at a 
depth of five or six feet. For many years experi- 
ments have been made in vain, in order to adapt this 
soil for sainfoin and lucern, and much expense in- 
curred, which could all have been saved, had the 
soil been previously analyzed. This example affords 
a most convincing proof of the importance of chemi- 
cal knowledge to an agriculturist. 

15. Surface-soil (A) of a sandy loam in the vicini- 
ty of Brunswick, celebrated for its beautiful crops 
of clover, rye, potatoes, and barley. The clover 
must, however, always be manured with gypsum. 
(B) is an analysis of the subsoil at the depth of 1^ 
foot. 100 parts contain : — 

(A) (B) 

Silica with coarse siliceous sand . . 94-274 95146 

Alumina 1-5G0 1-416 

Peroxide of iron with a little phosphoric acid 2"496 2-528 

Peroxide of manganese .... 0-240 0320 

Lime 0-400 297 ^ 

Magnesia 0-230 0-221 

Potash and soda 0102 060 

Sulphuric acid 0039 0-012 

Chlorine 0-005 a trace 

Humus soluble in alkaline carbonates . 0-444 . . . 

Humus 0-210 . . . 

100-000 100-000 

The best property of this soil is, that its inferior 
layers are nearly of the same composition as the 
superior, as far as the inorganic constituents are 
concerned. It is a soil upon which the plants 
mentioned above will seldom fail; and as it posses- 
ses a very good mixture to the depth of four or five 
feet, it would, doubtless, produce lucern also. 

16. Surface-soil (A) of a sandy loam in the vicinity 
of Brunswick. It produces excellent crops of oats 
and clover, when the latter is manured with gypsum. 



228 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



(B) Analysis of the subsoil taken from a depth of 
1| foot. 100 parts contain: — 



(A) 
Silica and siliceous sand . . . 94-430 

Alumina . . . . . 1.474 

Peroxide of iron with a little phosphoric acid 2-370 
Peroxide of manganese . . . a trace 

Lime, principally combined with silica U"680 

Magnesia, idevi .... 0-2'JO 

Potash 190 

Soda ..... 0-010 
Sulphuric acid .... a trace 

Chlorine ..... 0015 
Humus 0-541 



(B) 
89-660 
0980 
7-616 
a trace 
954 
0-520 

0150 

a trace 

a trace 

0120 



100000 100-000 

Both the surface and the sub-soil contain only 
traces of sulphuric acid. Hence the application of 
gypsum is attended with great benefit. Without 
doubt, marl and lime will be found of essential 
service. 

17. Soil from the environs of Brunswick, consisting 
principally of sand, and eminently remarked for its 
sterility. It was, however, much improved by ma- 
nuring it with marl which contained 24 per cent, of 
lime, together with magnesia, manganese, potash, 
soda, gypsum, and common salt. 100 parts of the 
soil contained : — 



Silica and siliceous sand . 


. 95-841 


Alumina .... 


0-600 


Protoxide and peroxide of iron 


. 1800 


Peroxide of manganese 


a trace 


Lime in combination with silica . 


. 038 


Magnesia, idem 


006 


Potash ..... 


. 0-002 


Soda ..... 


0-003 


Phosphoric acid combined with iron 


. 198 


Sulphuric acid 


0-002 


Chlorine ..... 


. 0-006 


Humus .... 


1-504 



100000 



Here another proof is presented, that a soil may 
be very rich in humus and yet be very poor as re- 
gards fertility. By means of the marl, the inorganic 
ingredients of the plants are furnished to the soil, 
•which contains them in very small quantity. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 229 

18. The soil of a very fertile loam from the vicin- 
ity of Walkenried. 100 parts contain: — 

Silica, with coarse-grained siliceous sand . 88-456 

Alumina ...... 0650 

Peroxide and protoxide of iron, accompanied by much 

magnetic iron sand .... 5-608 

■ Peroxide of manganese .... 0-560 

Carbonate of lime ..... 1-063 

Carbonate of magnesia .... 1'688 

Potash combined with silica . . . 0-040 

Soda combined with silica . . . O-Ol'J 

Phosphate of lime ..... 0035 

Sulphate of lime ..... a trace 

Common salt . . . . . 005 

Humus soluble in alkalies . . . 0-550 

Humus with several azotized organic remains . 1-333 

100-000 

Gypsum acts most excellently upon this land. 
The soils in the southern range of the Harz moun- 
tains are particularly remarked for containing more 
magnesia than lime. Even the different varieties 
of marl contain a considerable quantity of magnesia. 
Thus in a specimen of marl obtained from the vi- 
cinity of Walkenried, I obtained 55| per cent, car- 
bonate of lime, and 30^ per cent, carbonate of mag- 
nesia ; in another 41 per cent, lime, and 11 per cent, 
magnesia 5 and in a third, 47| per cent, lime, and 
13| per cent, magnesia. Most of these soils contain 
also I, — 1 per cent, of gypsum, and |, — 1 per cent, 
phosphate of lime, and are, therefore, well fitted for 
manuring other lands. 

19. Subsoil of a loam from a depth of 1| foot. It 
occurs in the vicinity of Brunswick. The surface- 
soil is remarkable on account of producing beautiful 
red clover on being manured with gypsum ; although 
the soil itself contains only traces of lime, magnesia, 
potash, and phosphoric acid. 100 parts of the sub- 
soil contained : — 

Silica and coarse siliceous sand . . . 88-980 

Alumina ..... 2-240 

Protoxide and peroxide of iron . . • 3-840 

Peroxide of manganese , . . a trace 

Carbonate of lime .... 2720 

Carbonate of mao-nesia . . . 0*600 

Potash and soda ..... 0-095 

20 



230 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Phosphate of lime 
Sulphate of lime 
Common salt 



1-510 

a trace 

0015 

100000 



At a greater depth than the subsoil of which the 
analysis is here given, the soil passes into marl, 
which contains 20| per cent, of carbonate of lime. 
The sulphuric acid deficient in the soil was supplied 
by means of the gypsum. 



SOILS IN THE KINGDOM OF HANOVER. 

20. (A) Analysis of a barren heath-soil from 
Aurich in Ostfriesland ; (B) a sandy soil containing 
much humus but also sterile; (C) a sandy soil 
possessing the same characters as B. 100 parts 
contained: — 





(A) 


(B) 


(C) 


Silica and coarse siliceous sand 


. 95-778 


85-973 


96 721 


Alumina 


320 


03-20 


0-370 


Protoxide and peroxide of iron 


. 0-4()0 


440 


0480 


Peroxide of manganese 


a trace 


a trace 


a trace 


Lime 


. 0-286 


0160 


0005 


Magnesia 


060 


0-240 


0-080 


Soda 


. 036 


012 


0.036 


Potash . _ . 


a trace 


a trace 


a trace 


Phosphoric acid 


. a trace 


a trace 


a trace 


Sulphuric acid .... 


a trace 


a trace 


a trace 


Ciilorine in common salt 


. 0052 


0019 


058 


Humus 


768 


4-636 


800 


Vegetable remains 


. 2-300 


8-200 


1450 



100-000 100-000 100 000 
21. Analysis of the clayey subsoil of a moor, 
which, after being burned, is used as a manure to 
the above Soils A, B, C. 100 parts contain : — 

Silica and siliceous sand . . . 87-219 

Alumina ...... 4-200 

Peroxide of iron with a little phosphoric acid . 5.200 

Peroxide of manganese . . . 0-310 

Lime ...... 0-320 

Magnesia . ^ . . . . . 380 

Potash principally combined with silica . 0-130 

Soda principally combined with silica . . 0-274 
Sulphuric acid combined with lime, magnesia, and 

potash . . ... 0-965 

Chlorine ..... 0-002 

Humus ...... 1000 

100000 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 231 

By comparing this analysis with that of the three 
soils which have preceded, it will be observed that 
this subsoil is fitted to impart to them those mineral 
ingredients in which they are deficient. 

22. Surface soil of a barren heath in the vicinity 
of Walsrode in Luneberg. 100 parts by weight 
contain : — 

Silica and siliceous sand .... 922 16 

Alumina ..... 0-266 

Peroxide of iron . • . . . 0-942 

Protoxide of iron .... 0-394 

Peroxide of manganese .... a trace 

Lime, in combination with silica, sulphuric acid, 

and humus ..... 1-653 

Magnesia, in combination with silica . . 0036 

Potash, principally in combination with silica 0038 

Soda . . . . . .a trace 

Phosphoric acid . . . .a trace 

Sulphuric acid ..... 0051 

Chlorine . . . . .a trace 

Humus, soluble in alkaline carbonates . . 2 084 

Humus ...... 1-900 

Resinous matter ..... 0-420 



100-000 



This soil contains a large quantity of protoxide of 
iron, which, together with a deficiency of phosphoric 
acidj is the cause of its sterility. But when this 
land was manured with the ashes of peat, it was 
rendered much more fertile. The ashes used for this 
purpose were found to contain in 100 parts : — 

Silica, with siliceous sand . . . 96-352 

Alumina ..... 1859 

Peroxide and protoxide of iron, with a little phos- 
phoric acid ..... 1120 

Peroxide of manganese . . . 0160 

Lime ...... 0112 

Magnesia ..... 0-141 

Potash ...... 0-093 

Soda . . . . . .0 007 

Sulphuric acid ..... 0-152 

Chlorine ..... 0004 

100 000 

The ashes, on exposure to the air, absorbed am- 
monia. 

23. Analysis of a very fertile loamy soil from Got- 
tingen. It is very rich in humus, and produces beau- 



232 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



tiful crops of peas, beans, lucern, and beet. The 
sieve separates from 100 parts of the soil : — 

Small stones, principally limestone . . I 

Quartzy sand, with a little magnetic iron sand . 15 

Earthy part . . . . . .84 



100 
, consists 

83-298 
1413 
3-715 



100 parts of the soil, freed from stones 
of: — 

Silica, and fine siliceous sand 

Alumina, combined with silica 

Alumina, partly in combination with humus 

Peroxide and protoxide of iron, in combination 

with silica ..... 0*724 
Peroxide and protoxide of iron, partly free and 

partly in combination with humus . . 2-244 

Peroxide and protoxide of manganese . 0-280 
Lime, with coal of humus, sulphur, and phosphoric 

acid ...... 1-814 

Magnesia, combined with silica . . 0-422 

Magnesia, combined with humus . • . 0-400 

Potash ...... 0-003 

Soda . .... 0001 

Phosphoric acid . . . . 01 66 

Sulphuric acid . . • . . 0-069 

Chlorine ...... 0002 

Carbonic acid (as carbonate of lime) . . 440 

Humus, soluble in alkalies . . . 789 

Humus, with a little water . . . 3'250 

Nitrogenous matter .... 0-960 

Resinous matter . . . . .a trace 

100 000 
The subsoil is of the same composition as the sur- 
face, with this difference only, that it contains more 
potash, soda, and chlorine,* and is interspersed with 
fragments of fresh-water shells. Hence it is that 
the soil produces the deep-rooted plants in such lux- 
uriance. 

24. Soil of a sterile moor, which had been burned 
three times, and upon which buckwheat had been 
cultivated. 100 parts contained: — 

Humus, soluble in alkalies . . . 9-250 

Vegetable remains, charcoal, quartzy sand, and 

earthy particles ..... 90-750 

100- 000 

* The portion of the surface-soil subjected to analysis was taken from 
the field after long-continued rain. Hence the small quantity of salts 
of potash and soda. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



233 



100 parts by weight left, afi 
of ashes. 100 parts of these 

Silica and siliceous sand 

Alumina 

Peroxide of iron 

Peroxide of manganese 

Carbonate of lime . 

Carbonate of magnesia . 

Potash 

Soda 

Phosphoric acid 

Sulphate of lime (gypsum) 

Chlorine 



er ignition, 10 parts 
ishes consisted of: — 



79-GOO 
6-288 
0-857 
0-400 
7-652 
1-640 
0080 
0-028 
0-215 
3235 
0-005 



100000 
Soils such as this, after having been burned seve- 
ral times, and made to produce buckwheat, are com- 
pletely deprived of their potash and soda; and in 
consequence of this are rendered quite barren. Hence 
it is that ashes of wood exert such an astonishing 
effect upon them. 

25. Analysis of a very fertile loamy sand, from 
Osnabriick, near Rotherfeld. It is remarkable for 
being manured only once every 10 or 12 years, and 
bears beautiful wheat as the last crop. 100 parts 
contain : — 

Silica, with coarse siliceous sand . . . 86 200 

Alumina ..... 2000 

Peroxide and protoxide of iron, with a little phos- 
phoric acid ..... 2-900 

Peroxide of manganese .... 0100 

Carbonic acid, and a little phosphate of lime . 4-160 

Carbonate of magnesia .... 0-520 

Potash and soda .... 0-035 

Phosphoric acid ..... 0-020 

Sulphuric acid ..... 0021 

Chlorine ...... 0010 

Humus, soluble in alkaline carbonates . 544 

Humus ...... 3-370 

Nitrogenous matter .... 0-120 

100-000 
The soil in question lies on the southern exposure 
of a hill, which consists of layers of limestone and 
marl. The rain-water penetrates through these lay- 
ers, and becomes saturated with the soluble salts 
contained in them, such as potash, gypsum, common 
salt, lime, magnesia, and saltpetre. It afterwards 
20* 



234 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

reaches the soil, and manures it with these ingredi- 
ents. It is only in this manner that we are enabled 
to explain the fertility of this soil ; for, reasoning 
from its chemical composition, we should be induced, 
a priori, to suppose that it would be barren. At the 
base of this hill, certain portions of the land are 
covered with calcareous tuff, containing the above 
salts : a fact which proves that the water which pen- 
etrates through the soil must also contain them in 
solution. The large proportion of humus exhibited 
by the analysis depends upon the nature of the ma- 
nure with which it was treated. 

26. Analysis of a heavy alluvial soil, from Norden. 
100 parts contain: — 

Silica, and very fine siliceous sand . . 84*543 



Alumina 

Peroxide of iron 

Peroxide of manganese 

Lime . . • . 

Magnesia .... 

Potash .... 

Soda, in combination with silica 

Phosphoric acid, in combination with lime 

Sulphuric acid 

Chlorine . . . • 

Humus, soluble in alkalies 



3-4.58 
3-488 
0-560 
0-319 
0-740 
a trace 
6004 
0-260 
0-008 
0008 
0-416 



Humus and nitrogenous matter . . 0196 

100-000 

The portion of the soil subjected to analysis was 
taken at a depth of 10 inches, from a field w^hich 
had received no manure for several years. It had 
previously produced in succession barley, beans, 
wheat, and grass, the latter for two years. The soil 
is remarkable, in a chemical point of view, from the 
large quantity of soda which it contains. Although 
the sulphuric acid, chlorine, and potash, are present 
in small quantity, yet this does not present any bar- 
rier to the development of the plants, as the surface- 
soil is 18 inches in depth. 

27. Analysis of a heavy alluvial soil in the vicinity 
of Norden. 100 parts contain; — 

Silica, and very fine siliceous sand . . 79-174 

Alumina ..... 3016 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



235 



Peroxide of iron 


4-960 


Peroxide of manganese 


. 0-600 


Carbonate of lime 


2-171 


Carbonate of magnesia 


. 2 226 


Potash, in combination with silica 


0-025 


Soda, idem . . , • 


. 6-349 


Phosphoric acid 


0-534 


Sulphuric acid .... 


. a trace 


Chlorine .... 


005 


Humus, soluble in alkalies 


. 0-782 


Humus, with nitrogenous matter 


0-LS8 



100.000 
The specimen for analysis was taken at a depth 
of 10 inches from the surface of a field, which had 
been manured five years previously, and had pro- 
duced since that time rape, rye, wheat, and beans. 
The crops of all these were plentiful, and of excel- 
lent quality. It is singular that this soil, which 
contains such a small proportion of gypsum, should 
be adapted for the cultivation of beans, and must 
be ascribed to the depth of the surface-soil. Yet, 
notwithstanding this, gypsum would form a beneficial 
manure to the land. 

28. Analysis of very fertile alluvial soil, from 
Honigpolder; no manure had ever been applied to 
it. 100 parts contain: — 

Siliceous sand separated by the sieve . . 4-5 

Earthy portion of the soil 



100 parts of the latter consisted of: — 

Silica, and fine siliceous sand 

Alumina .... 

Peroxide of iron .... 

Peroxide of manganese 

LAme ..... 

Magnesia .... 

Potash, principally in combination with silica 

Soda, idem .... 

Phosphoric acid combined with lime . 

Sulphuric acid, idem 

Chlorine (in common salt) 

Carbonic acid, combined with lime 

Humus soluble in alkalies 

Humus .... 

Nitrogenous matter .... 

Water ..... 



95-5 
1000 



64-800 
5.700 
6100 
090 
5-880 
0-840 
0-210 
0393 
0-430 
0-210 
0-201 
3-920 
2-540 
5-600 
1-582 
1504 



100-000 



236 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Corn has been cultivated for seventy years upon 
this soil, which has never received dung or any other 
kind of manure 5 it is, however, occasionally fallowed. 
The subsoil retains the same composition as the 
surface-soil for a depth of 6 — 12 feet, so that it may 
be considered inexhaustible. When one portion of 
the soil is rendered unfit for use, the inferior layers 
are brought up to the surface. , 

29. Analysis of a soil from Rahdingen, near Balje. 
In this case the sea has assisted in the formation of 
the soil. The field yielded beautiful corn after being 
manured with stable dung, being particularly re- 
marked for its fine crops of wheat, beans, and winter 
barley. 100 parts contain: — 



Silica, siliceous sand, and silicates 


. 87-012 


Alumina . . ... 


4-941 


Peroxide of iron 


. 2430 


Peroxide of manganese 


0-192 


Lime ..... 


. 0-292 


Magnesia .... 


0-145 


Potash and soda soluble in water 


. 0-005 


Phosphoric acid 


0114 


Sulpliuric acid 


. 0-074 


Chlorine (in common salt) 


0-003 


Humus, soluble in alkaline carbonates . 


. 0-658 


Humus .... 


2-668 


Nitrogenous matter 


. 1-412 


Water .... 


0042 



100000 

30. Soil of a field remarkable for producing large 
crops of hemp and horse-radish. 100 parts con- 



sisted of: — 






Silica and siliceous sand 




, 84-021 


Alumina 




4-498 


Peroxide of iron 




. 5120 


Peroxide of manganese 




2-080 


Lime 




. 942 


Magnesia 




1-740 


Potash 




. 0-050 


Soda 




0012 


Phosphoric acid . 




. 0-482 


Sulphuric acid 




0-012 


Chlorine 




. 0-008 


Humus, soluble in alkaline 


carbonates 


0-807 


Humus and nitrogenous matter . 


. 0-138 



100 000 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



237 



31. Surface-soil of a field near Drackenburs; ; it 



produces very bad red clover. 100 par 

Silica, with very fine siliceous sand 
Alumina .... 

Peroxide of iron 

Peroxide of manganese . . 

Lime . . . • . 

Magnesia . . . 

Potash combined with silica . . 

Soda, idem .... 
Phosphoric acid, in combination with lime 
Sulphuric acid 

Chlorine .... 

Humus and nitrogenous matter . 

Humus, soluble in alkaline carbonates 



ts contain: — 



92014 
'i-652 
3192 
0480 
0243 
0-700 
0125 
0026 
0-078 
a trace 
a trace 
0150 
0-340 



100-000 



The cause that clover will not flourish on this soil 
is probably due to the deficiency of gypsum and 
common salt. 

32. Surface-soil of a field near Paddingbuttel. 
This field is particularly adapted for the growth of 
red clover. 100 parts consist of: — 



Silica and siliceous sand 

Alumina .... 

Peroxide of iron 

Peroxide of manganese 

Lime ..... 

Magnesia .... 

Potash, principally in combination with silica 

Soda, idem . . . • 

Phosphoric acid .... 

Sulphuric acid 

Chlorine (in common salt) 

Humus, soluble in alkaline carbonates 

Humus, with nitrogenous matter 



93-720 
1-740 
2-060 
0-320 
0121 
0-700 
0f>2 
0-109 
0-103 
0005 
00.50 
0-890 
0120 

100-000 



SOILS IN BOHEMIA. 



33. Surface-soil of a very fertile field in the prov- 
ince of Dobrawitz and Lautschin. 100 parts gave 

4-286 
95 714 



Siliceous sand, with much magnetic iron sand 
Earthy part separated by the sieve 



lOO'OOO 



238 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



An aqueous infusion of the soil contained gypsum, 
common salt, magnesia, and humus. 100 parts of 
the soil gave : — 



Silica . . . • 

Alumina 

Protoxide and peroxide of iron 

Peroxide of manganese 

Lime .... 

Magnesia 

Potash, in combination with silica 

Soda, idem (principally) 

Phosphoric acid, in combination with lime 

Sulphuric acid, idem 

Ciilorine (in common salt) 

Humus, soluble in alkalies 

Humus .... 

Nitrogenous matter 



89-175 
2-652 
3-136 
0-320 
1-200 
1040 
0-075 
0354 
0-377 
0081 
066 
0-9-20 
0-4.56 
0-208 

100000 



34. Surface-soil of a very fertile field in the prov- 
ince of Dobrawitz and Lautschin. 100 parts of the 
earth consisted of: — 



Siliceous sand, with a little magnetic iron sand 
Finer part separated by the sieve 



43-780 
56-220 



100-000 

100 parts yielded to water 0*175 part of salts, 
consisting of common salt, gypsum, magnesia, and 
huraic acid. 100 parts, by weight, of the earth con- 
sisted of: — 



Silica ..... 


. 89.634 


Alumina .... 


3224 


Protoxide and peroxide of iron 


. 2-944 


Peroxide of manganese . 


M60 


Lime ..... 


. 0-349 


Magnesia .... 


0-3U0 


Potash, in combination with silica 


. 0-160 


Soda, idem .... 


0-428 


Phosphoric acid, in combination with lime 


. 0-246 


Sulphuric acid, idem 


0-005 


Chlorine (in common salt) 


. 0012 


Humus, soluble in alkalies 


0-750 


Humus ..... 


. 0-340 


Nitrogenous matter . . . . 


0-448 



100-000 



35. Analysis of a soil formed by the disintegration 
of basalt. 100 parts of the earth consisted of: — 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



239 



Siliceous sand, with very much magnetic iron sand 8-428 
Earthy portion of the soil .... 91-572 

100-000 

The aqueous infusion of the earth contained only 
traces of common salt and gypsum, with humus, 
lime, and magnesia. 100 parts consisted of: — 



Silica ..... 


. 83-642 


Alumina ..... 


3-978 


Protoxide and peroxide of iron 


. 5312 


Peroxide of manganese 


0-960 


Lime ..... 


. 1976 


Magnesia ..... 


0-650 


Potash, in combination with silica 


. 0080 


Soda, idem ..... 


0145 


Phosphoric acid, in combination with lime 


. 273 


Sulphuric acid, ideni . . . . 


a trace 


Humus, soluble in alkaline carbonates . 


. 1-270 


Chlorine . . . . . . 


a trace 


Humus, ..... 


. 0234 


Nitrogenous matter .... 


1-480 



100000 
Manure consisting of gypsum, common salt, or 
ashes of wood, would be highly conducive to the 
fertility of this land. 



SOILS IN THE " MARKGRAFSCHAFT MAHREN." 

36. Surface-soil of a field very remarkable for its 
fertility. The field is called Haargi^ahen, and is 
situated near the village of Nebstein. It has never 
been manured or allowed to lie fallow and ye^ has 
produced for the last 160 years the most beautiful 
crops ; thus furnishing a remarkable example of un- 
impaired fertility. 100*000 parts of this soil con- 
sisted of: — 

Coarse and fine siliceous sand, with a little mag- 
netic iron sand ..... 35400 
Earthy matter ..... 64 600 



100000 



100 parts of the earth yielded to water 0-010 sul- 
phuric acid, 0-010 chlorine, 0-007 soda, 0-012 mag- 
nesia, 0-010 potash, with a little silica, humus, and 



240 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



nitrogenous matter, but no appreciable trace of ni- 
trates. 100 parts of the soil contained: — 



Silica ..... 


. 77-209 


Alumina ..... 


8-514 


Peroxide of iron .... 


. 6-592 


Peroxide of manganese 


1-520 


Lime . . . . . ^ 


0-927 


Magnesia ..... 


1-160 


Potash, principallj in combination with silica 


. 0-140 


Soda, idem ..... 


0640 


Phosphoric acid, combined with lime and iron 


6-651 


Sulphuric acid, combined with lime . 


0-011 


Chlorine (in common salt) 


0010 


Humus, soluble in alkalies 


0-978 


Humus ..... 


. 0-540 


Nitrogenousjntiatter .... 


1-108 



100-000 
It is apparent from the above analysis that, not- 
withstanding the long period during which this land 
has been cultivated without manure, it still remains 
very rich in matters adapted for the nutrition of 
plants. 



SOILS IN HUNGARY. 



37. Analysis of a very fertile soil from Esakang. 
100 parts of the earth contained : — 



Very fine siliceous sand 
Earthy matter 



. 2-8-20 
97180 

100 000 



The aqueous decoction of the soil contained princi- 
pally gypsum, common salt, silica, magnesia, and 
humus. 100 parts of the soil yielded: — 



Silica ..... 


76-038 


Alumina ..... 


4-654 


Peroxide and protoxide of iron 


6112 


Peroxide of manganese 


0-900 


Carbonate of lime 


3771 


Carbonate of magnesia 


4066 


Potash, combined with silica 


0-030 


Soda, combined with silica . . , 


1-379 


Phosphoric acid, combined with lime 


0-546 


Sulphuric acid .... 


0021 


Chlorine in common salt . 


0015 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



241 



Humus, soluble in alkalies 

Humus 

Nitrogenous organic matter 



M60 
1100 
0-208 

100000 



Subsoil of the same field at a depth of two feet. 
100 parts consist of: — 



Very fine siliceous sand with scales of mica 
Earth separated by the sieve 



100 parts of the earth contain : — 

Silica .... 

Alumina .... 

Peroxide and protoxide of iron 

Peroxide of manganese 

Carbonate of lime 

Carbonate of magnesia 

Potash, combined with silica 

Soda, principally combined with silica 

Phosphoric acid, combined with lime 

Sulphuric acid, idem . 

Chlorine in common salt 

Humus, soluble in alkalies 

Humus, witli nitrogenous organic matter 



2-408 
97-592 



100-000 



59-581 
3-224 
4-896 
0-720 
17-953 
11-075 
0-150 
0-891 
846 
0-004 
0-004 
0-536 
0120 

100-000 



BELGIUM. 

38. Surface-soil of a field distinguished for its fer- 
tility. It had received no manure for twelve years pre- 
vious to the time at which the analysis was executed. 
The rotation of crops for the latter nine years was as 
follows : — 1. beans, 2. barley, 3. potatoes, 4. winter 
barley with red clover, 5. clover, 6. winter barley, 
7. wheat, 8. oats ; during the ninth year it was 
allowed to lie fallow. The soil is more clayey than 
loamy, and of a very fine grain. Water extracted 
from the soil, 0-013 soda, 0-002 lime, 0-012 magnesia, 
0-009 sulphuric acid, 0-003 potash, 0-003 chlorine, 
with traces of silica and humus. 100 parts con- 
tained : — 



Silica 

Alumina 

Peroxide and protoxide of iron 

Peroxide of manganese 

Carbonate of lime 

21 



64-517 
4-810 
8316 
0800 
9-403 



242 



ON THE CHEMICAL CONSTITUENTS OF SOILS, 



Carbonate of magnesia 

Potash, principally combined with silica 

Soda .... 

Phosphoric acid 

Sulphuric acid 

Chlorine . . . 

Humus .... 



10-3G1 
0-100 
0013 
1-221 
00U9 
003 
0-447 

100-000 



ENGLAND. 



39. Surface-soil of a very fertile sandy field from 
the vicinity of Tunbridge, Kent, according to Davy. 
100 parts consisted of: — 



Loose stones and gravel 


. 13-250 


Sand and silica 


58-250 


Alumina . . . 


. 3250 


Peroxide of iron 


1-250 


Carbonate of lime . . . 


. 4-750 


Carbonate of magnesia 


0-750 


Common salt and extractive matter 


. 0-750 


Gypsum .... 


0-500 


Matter destructible by heat 


. 3-750 


Vegetable fibre 


3-500 


Water . • . . . 


. 5-000 


Loss ..... 


5-000 



100-000 

The great Davy, who was convinced of the impor- 
tance of the inorganic constituents of soils, has 
omitted to detect the phosphoric acid, potash, soda, 
and manganese. All these must have been present 
in the soil, for we are informed that it produced 
good hops, for which these ingredients are indis- 
pensable. 

40. A good turnip soil from Holkham, Norfolk, 
yielded to Davy: — 



Siliceous sand 

Silica . . 

Alumina 

Peroxide of iron 

Carbonate of lime 

Vegetable and saline matter 

Moisture 



l'C66 
12^ 
0-334 
7-000 
0550 
0-334 



100-000 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 243 

In this case also, phosphoric acid, manganese, 
potash, magnesia, &c., have escaped detection by 
this acute chemist; yet doubtless they must be 
present in the soil, for we are informed that it pro- 
duces good turnips. 

41. An excellent wheat soil from the neighborhood 

of West Drayton, Middlesex, according to Davy. 

100 parts contained : — 

Sand and silica .... 72-800 

Alumina ..... 11-600 

Carbonate of lime .... 11-200 

Humus and moisture , . . 4-400 

100-000 
This analysis has been executed so imperfectly, 
that it only conveys a very feeble representation of 
the nature of the soil. A soil which bears good 
wheat must contain phosphate of potash, soda, chlo- 
rine, and sulphuric acid ; yet none of these are exhib- 
ited by the analysis. 

42. Surface-soil of a fertile field in the neighbor- 
hood of Bristol. 100 parts contained: — 

Silica and siliceous sand . . , 60*000 

Alumina ..... 12000 

Peroxide of iron .... 3*500 

Lime (carbonate) .... 7-500 

Magnesia ..... 0-500 

Humus ...... 1*250 

Saline and extractive matter . . 0750 

Water ...... 14-500 



100000 
Davy has made several analyses of various fertile 
soils, and since his time numerous other analyses 
have been published ; but they are all so superficial, 
and in most cases so inaccurate, that we possess no 
means of ascertaining the composition or nature of 
English arable land. 



SWEDEN. 



43. Surface-soil of a field which produces the most 
abundant crops, and has never been manured. (Ber- 
zelius.) 100 parts consist of: — 



244 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Siliceous sand .... 

Silica ..... 

Alumina ..... 

Phosphates of lime and iron 

Carbonate of lime .... 

Carbonate of magnesia 

Insoluble extractive matter . . 

Insoluble extractive matter destructible by heat 

Animal matter .... 

Resin ..... 

Loss ..... 



57-900 
14-500 
2-000 
6-000 
11100 
1-000 
1-250 
4-0(t0 
1-600 
0250 
400 



100-000 

This great chemist has strangely omitted to detect 
in the soil potash, soda, chlorine, sulphuric acid, and 
manganese. As this soil is eminent for its fertility, 
there cannot be the slightest doubt that all these 
ingredients must have existed in it in notable quan- 
tity. 



ISLAND OF JAVA. 



44. A very fine-grained loamy soil, colored yellow 
by peroxide of iron, consisted of: 



Silica and siliceous sand 

Alumina 

Peroxide and protoxide of iron 

Peroxide of manganese 

Lime 

Magnesia 

Potash, principally in combination with silica 

Soda, idem 

Phosphoric acid 

Sulphuric acid 

Chlorine 

Humus . . . 

Water, with carbonic acid 



: — 






. 67-660 


^ , 


13-572 


^ 


. 10-560 




1-640 




. 0-912 




0-570 


th silica 


. 0030 




0-184 


, 


. 0-391 


^ , 


0-038 


, 


. OOIO 


^ , 


0368 


• 


. 4-065 



100-000 



WEST INDIES (pORTO RICO). 

45. Surface-soil of a very barren field. 100 parts 
contained : — 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



245 



Silica and siliceous sand 


70-900 


Alumina ..... 


6-996 


Peroxide, and protoxide of iron (much magnetic 




iron sand) .... 


6-102 


Peroxide of manganese 


0-800 


Lime . . . , . 


2-218 


Magnesia . . . . . 


3-280 


Potash ..... 


0-130 


Carbonate of soda .... 


6-556 


Phosphoric acid, combined with lime 


1-362 


Sulphuric acid, combined with lime 


0-149 


Chlorine in common salt 


0067 


Humus, soluble in alkalies 


0540 


Humus ..... 


1-500 



100-000 



This soil is improved by gypsum. Its sterility is 
due to the excessive quantity of carbonate of soda 
which is present. 



NORTH AMERICA. 



46. Surface-soil of alluvial land in Ohio, remark- 
able for its great fertility. 100 parts consisted of: — 



Silica and fine siliceous sand 




79-538 


Alumina .... 


, 


7-306 


Peroxide and protoxide of iron (much magnetic 




iron sand) 


. 


5-824 


Peroxide of manganese 


. 


1-320 


Lime .... 


, 


0-619 


Magnesia 




1024 


Potash, principally combined with silica 




0-200 


Soda .... 




024 


Phosphoric acid, combined with lime and 


oxide of 




iron .... 




1-776 


Sulphuric acid, combined with lime . 




0-122 


Chlorine 


, 


0036 


Humus, soluble in alkalies 


, 


1-950 


Nitrogenous organic matter 




0-236 


Wax and resinous matter 


• 


0025 



100000 

47. (A.) Surface-soil of a mountainous district in 
the neighborhood of Ohio. (B.) analysis of the 
subsoil. This soil is also distinguished for its great 
fertility. 100 parts contain: — 
21* 



246 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



(A) 


(B) 


. 87-143 


94-261 


5-666 


1-376 


. 2220 


2-336 


0-360 


1-200 


. 0-564 


243 


0-312 


0-310 


a . 120 > 

0-025 5 


0-240 


0060 


a trace 


0-027 


0034 


0-036 


a trace 


1-304 




1072 




0-080 




1011 





Silica with fine siliceous sand 

Alumina 

Peroxide and protoxide of iron 

Peroxide of manganese . 

Lime 

Magnesia 

Potash, principally combined with siUca 

Soda .... 

Phosphoric acid 

Sulphuric acid . 

Chlorine 

Humus, soluble in alkalies 

Humus 

Carbonic acid, combined with lime 

Nitrogenous organic matier 

100-000 100-000 * 

In the preceding part of the chapter we have in- 
serted a number of analyses of various soils, as well 
as the conclusions deduced from them, by means of 
which the farmer may be enabled to ascertain the 
manures best adapted for each variety of soil. By 
inspecting the analyses of the sterile soils, it will be 
apparent that it is in the power of chemistry to point 
out the causes of their sterility. The general cause 
which conduces to the sterility of soils is either the 
absence of certain constituents indispensable for the 
growth of plants, or the presence of others, which 

* Soil from Chelmsford, Massachusetts, on the Merrimack river, 

which has produced a large crop of wheat for 20 years, with only one 

failure, analyzed by Dr. Dana. 100 parts contain : — 

Soluble geine ..... 3.9228 

Insoluble " . . . . . 2-6142 

Sulphate of lime ..... -7060 
Phosphate of " . . . . -9082 

Silicates (silica, alumina, iron &c.) . . 91-8485 

No trace of carbonate of lime, or of alkaline salts, could be discovered. 
Soil from Maine, analyzed by Dr. Jackson, has produced 48 bushels 

of wheat per acre. 

Water . . . . . .50 

Vegetable matter .... 17-5 

Silica 54-2 

Alumina ..... 106 

Subphosphate of alumina . . . .3-0 

Peroxide of iron .... 7-0 

Oxide of manganese . . . . .1-0 

Carbonate of lime . . . . 15 



99-8 
From Hitchcock's Final Report, p. 29. 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 247 

exert an injurious or poisonous action. The analy- 
ses are those of Dr. Sprengel, — a chemist who has 
unceasingly occupied himself for the last twenty 
years in endeavoring to point out the importance 
of the inorganic ingredients of a soil for the develop- 
ment of plants cultivated upon it. He considers as 
essential all the inorganic bodies found in the ashes 
of plants. Now, although we cannot coincide with 
him in the opinion, that iron and manganese are in- 
dispensable for vegetable life, (for these bodies are 
found as excrementitious matter only in the bark, 
and never form a constituent of an organ,) yet we 
gratefully acknowledge the valuable services which 
he has rendered to agriculture, by furnishing a natu- 
ral explanation of the action of ashes, marl, &c., in 
the improvement of a soil. Sprengel has shown, 
that these mineral manures afford to a soil alka- 
lies, phosphates, and sulphates; and further, that 
they can exert a notable influence only on those 
soils in which they are absent or deficient. In a 
former chapter of this book I have endeavored to 
point out the importance of considering these con- 
stituents as intimately connected with the vital pro- 
cesses of the vegetable organism, and have shown 
that the different families of plants contain unequal 
quantities of inorganic ingredients. This subject 
has been left unexamined by Sprengel, yet it is one 
of much importance ; for the application of manures 
must be regulated by the composition of the plants 
which are cultivated on any particular soil. Still, 
the composition of the soil must always be kept in 
view. Thus it would be perfect extravagance to 
manure certain soils with marl, ashes, or gypsum; 
whilst, on the contrary, these compounds would pro- 
duce the most beneficial results on other lands. 

In a former part of the work, the principal action 
of gypsum upon vegetation was ascribed to the de- 
composition and fixation of the carbonate of ammonia 
contained in rain-water; but gypsum exerts a two- 
fold action. The power of decomposing carbonate 



248 ON THE CHEMICAL CONSTITUENTS OF SOILS. 

of ammonia, and of fixing the ammonia, is not pecu- 
liar to gypsum, but is shared also by other salts of 
lime (chloride of calcium, for example). But it acts 
also as a sulphate, and when useful as such cannot 
be replaced by any other salt of lime which does not 
contain sulphuric acid. 

Hence gypsum can be replaced as a manure only 
by a mixture of a salt of lime with ammonia, and a 
salt of sulphuric acid. Sulphate of ammonia can 
therefore_^be substituted for gypsum, and exerts a 
more rapid and effectual action. In France, sul- 
phuric acid has been poured upon the fields after the 
removal of the crops, and has been found to form a 
good manure. But this is merely a process for form- 
ing gypsum in situ; for the soils upon which it is 
applied contain much lime, which enters into com- 
bination with the sulphuric acid. It would certainly 
be much more advantageous to form sulphate of am- 
monia by adding the acid to putrefied urine, and to 
apply this mixture to the field. 



APPENDIX TO PART I. 



EXPERIMENTS AND OBSERVATIONS ON THE ACTION OF CHARCOAL 
FEOM WOOD ON VEGETATION. 

BY EDWARD LUCAS.* 

" In a division of a low hothouse in the botanical garden 
at Munich, a bed was set apart for young tropical plants, 
but instead of being filled with tan, as is usually the case, 
it was filled with the powder of charcoal, (a material which 
could be easily procured,) the large pieces of charcoal 
having been previously separated by means of a sieve. 
The heat was conducted by means of a tube of white iron 
into a hollow space in this bed, and distributed a gentle 
warmth, such as tan communicates, when in a state of fer- 
mentation. The plants placed in this bed of charcoal quick- 
ly vegetated, and acquired a healthy appearance. Now, as 
always is the case in such beds, the roots of many of the 
plants penetrated through the holes in the bottom of the 
pots, and then spread themselves out ; but these plants 
evidently surpassed in vigor and general luxuriance plants 
grown in the common way, — for example, in tan. Several 
of them, of which I shall only specify the beautiful Thim- 
bergia alata, and the genus Pcireskim, throve quite aston- 
ishingly ; the blossoms of the former were so rich, that all 
who saw it affirmed, they had never before seen such a 
specimen. It produced also a number of seeds without 
any artificial aid, while in most cases it is necessary to ap- 
ply the pollen by the hand. The Peircskice grew so vigoi'- 
ously, that the P. acideata produced shoots several ells in 
length, and the P. grandifolia acquired leaves of a foot in 
length. These facts-, as well as the quick germination of 
the seeds which had been scattered spontaneously, and the 
abundant appearance of young Filices, naturally attracted 
my attention, and I was gradually led to a series of ex- 
periments, the results of which may not be uninteresting ; 

* See page 78. 



250 APPENDIX TO PART I. 

for, besides being of practical use in the cultivation of most 
plants, they demonstrate also several facts of importance 
to physiology. The first experiment which naturally sug- 
gested itself, was to mix a certain proportion of charcoal 
with the earth in which different plants grew, and to in- 
crease its quantity according as the advantage of the meth- 
od was perceived. An addition of § charcoal, for exam- 
ple, to vegetable mould, appeared to answer excellently for 
the Gesneria and Gloxinia, and also for the tropical Jlroidca 
with tuberous roots. The first two soon excited the atten- 
tion of connoisseurs, by the great beauty of all their parts 
and their general appearance. They surpassed very quick- 
ly those cultivated in the common way, both in the thick- 
ness of their stems and dark color of their leaves ; their 
blossoms were beautiful, and their vegetation lasted much 
longer than usual, so much so, that in the middle of Novem- 
ber, when other plants of the same kinds were dead, these 
were quite fresh and partly in bloom. Jlroidem took root 
very rapidly, and their leaves surpassed much in size the 
leaves of those not so treated ; the species which are reared 
as ornamental plants on account of the beautiful coloring 
of their leaves, (I mean, such as the Caladiinn bicolor, 
Pictwn, Pcecile, &.c.,) were particularly remarked for the 
liveliness of their tints ; and it happened here also, that 
the period of their vegetation was unusually long. A 
cactus planted in a mixture of equal parts of charcoal and 
earth throve progressively, and attained double its former 
size in the space of a few weeks. The use of the charcoal 
was very advantageous with several of the Bromeliacece 
and Liliacem, with the Citrus and Begonia also, and even 
with the PalincB. The same advantage was found in the 
case of almost all those plants for which sand is used, in 
order to keep the earth porous, when charcoal was mixed 
with the soil instead of sand ; the vegetation was always 
rendered stronger and more vigorous. 

" At the same time that these experiments were performed 
with mixtures of charcoal with different soils, the charcoal 
was also used free from any addition, and in this case the 
best results were obtained. Cuts of plants from different 
genera took root in it well and quickly ; I mention here 
only the Euphorbia fastuosa and fulgens which took root in 
ten days, Pandcmus utilis in three months, P. amaryllifolius, 
C/iamcedorea elalior in four weeks. Piper nigrum, Begonia, 
Ficus. Cecropia, Chiococca, Buddleya, Hakea, Phyllanlhus, 
Capparis, Laurus, Slifflia, Jacquinia Mimosa, Cactus, in 



ACTION OF CHARCOAL ON ATSGETATION. 251 

from eight to ten days, and several others, amounting to 
forty species, including Ilex and many others. Leaves, 
and pieces of leaves, and even pedunculi, or petioles, took 
root and in part budded in pure charcoal. Amongst others 
we may mention the foliola of several of the Cycadece, as 
having taken root, as also did parts of the leaves of the 
Begonia Telfairue, and Jacaranda brasUiensis ; leaves of the 
Euphorbia fastuosa, Oxalis Barrilieri, Ficus, Cyclamen, 
Polyantlies, Mesembryantheinum ; also the delicate leaves 
of the Lophospenniim and Marlynia, pieces of a leaf of the 
Jlgave americana ; tufts of Pinus, &lc. ; and all without the 
aid of a previously formed bud.* 

"Pure charcoal acts excellently as a means of curing 
unhealthy plants. A Durianthes excdsa, for example, which 
had been drooping for three years, was rendered com- 
pletely healthy in a very short time by this means. An 
orange tree which had the very common disease in which 
the leaves become yellow, acquired within four weeks its 
healthy green color, when the upper surface of the earth 
was removed from the pot in which it was contained, and a 
ring of charcoal of an inch in thickness strewed in its 
place around the periphery of the pot. The same was the 
case with the Gardenia. 

"I should be led too far were I to state all the results 
of the experiments which I have made with charcoal. The 
object of this paper is merely to show the general effect 
exercised by this substance on vegetation ; but the reader 
who takes particular interest in the subject will find more 
extensive observations in the ' Allgemeine Deutsche Garten- 
zeilung ' of Otto and Dietrich, in Berlin ; or Loudon's 
Gardener's Magazine, for March, 1841. 

"The charcoal employed in these experiments was the 
dust-like powder of charcoal from firs and pines, such as is 
used in the forges of blacksmiths, and may be easily pro- 
cured in any quantity. It was found to have most effect 
when allowed to lie during the winter exposed to the action 
of the air. In order to ascertain the effects of different 
kinds of charcoal, experiments were also made upon that 
obtained from the hard woods and peat, and also upon 

* Tlie cuttings of several of these plants being full of moisture, require 
to be partially dried before they are placed in tlie soil, and are with 
difficulty made to strike root in the usual method. The charcoal is 
probably useful from its absorbing and antiseptic power. The Hakea 
is extremely difficult to propagate from cuttings. All the Laurus tribe 
are obstinate, some of them have not rooted under three years from the 
time of planting. — W. 



252 APPENDIX TO PART I. 

animal charcoal, although I foresaw the probability that 
none of them would answer so well as that of pine wood, 
both on account of its porosity and the ease with which it 
is decomposed.* 

"It is superfluous to remark, that in treating plants in 
the manner here described, they must be plentifully supplied 
with water, since the air having such free access penetrates 
and dries the roots, so that unless this precaution is taken 
the failure of all such experiments is unavoidable. 

"The action of charcoal consists primarily in its pre- 
serving the parts of the plants with which it is in contact, 
— whethep-they be roots, branches, leaves, or pieces of 
leaves, — unchanged in their vital power for a long space 
of time, so that the plant obtains time to develop the organs 
which are necessary for its further support and propaga- 
tion. There can scarcely be a doubt also that the char- 
coal undergoes decomposition ; for after being used five to 
six years it becomes a coaly earth ; and if this is the case, 
it must yield carbon, or carbonic oxide, abundantly to the 
plants growing in it, and thus afibrd the principal substance 
necessary for the nutrition of vegetables.! In what other 
manner, indeed, can we explain the deep green color and 
great luxuriance of the leaves and every part of the plants, 
which can be obtained in no other kind of soil, according 
to the opinion of men well qualified to judge .'' It exercises 
likewise a favorable influence by decomposing and absorb- 
ing the matters excreted by the roots, so as to keep the 
soil free from the putrefying substances which are often 
the cause of the death of the spongiolce. Its porosity, as 
well as the power which it possesses of absorbing water 
with rapidity, and, after its saturation, of allowing all other 
water to sink through it, are causes also of its favorable 
effects. These experiments show what a close affinity the 
component parts of charcoal have to all plants, for every 
experiment was crowned with success, although plants 

* M Lucas has recently repeated these experiments, and found that 
the animal charcoal obtained by the calcination of bones possesses a 
decided advantage over all other kinds of charcoal, which he subjected 
to experiment. — Liebig's Jlnnalen^ Batid xxxix. Heft I. S. !27. 

t As some misconception has arisen regarding this explanation of the 
action of charcoal upon vegetation, and an idea propagated, that the 
introduction of these opinions into Ihis work incorporated them with 
those of Liebig, it is necessary to state that they are merely inserted 
here as part of the papers of M. Lucas. The true explanation has 
been given in a former part of the work, viz. that charcoal possesses 
the power of absorbing carbonic acid and ammonia from tiie atmo- 
sphere, which serve for the nourishment of plants. — Ed. 



ON A MODE OF MANURING VINES. 253 

belonging to a great many different families were sub- 
jected to trial." {Buchner's Repcrlorium, ii. Keilie, xix. 
Bd. S. 38.) 



ON A MODE OF MANURING VINES. 

The observations contained in the following pages should 
be extensively known, because they furnish a remaikable 
proof of the principles which have been stated in the pre- 
ceding part of the work, both as to the manner in which 
manure acts, and on the origin of the carbon and nitrogen 
of plants. 

They prove that a vineyard may be retained in fertility 
without the application of animal matters, when the leaves 
and branches pruned from the vines are cut into small 
pieces and used as manure. According to the first of the 
following statements, both of which merit complete con- 
fidence, the perfect fruitfulness of a vineyard has been 
maintained in this manner for eight years, and according 
to the second statement for ten years. 

Now, during this long period, no carbon was conveyed to 
the soil, for that contained in the pruned branches was the 
produce of the plant itselt^, so that the vines were placed 
exactly in the same condition as trees in a forest which 
received no manure. Under ordinary circumstances a 
manure containing potash must be used, otherwise the 
fertility of the soil will decrease. This is done in all wine- 
countries, so that alkalies to a very considerable amount 
must be extracted from the soil. 

When, however, the method of manuring now to be 
described is adopted, the quantity of alkalies exported in 
the wine does not exceed that which the progressive dis- 
integration of the soil every year renders capable of being 
absorbed by the plants. On the Rhine 1 litre of wine is 
calculated as the yearly produce of a square metre of land 
(10'8 square feet English). Now if we suppose that the 
wine is three-fourths saturated with cream of tartar, a pro- 
portion much above the truth, then we remove from every 
square metre of land with the wine only TS gramme of 
potash. 1000 grammes (1 litre) of champagne yield only 
1 '54, and the same quantity of Wachenheimer I 72 of a 
residue which after being heated to redness is found to 
consist of carbonates. 

One vine-stock, on an average, grows on every square 
22 



254 APPENDIX TO PART I. 

metre of land, and 1000 parts of the pruned branches con- 
tain 56 to 60 parts of carbonate, or 38 to 40 parts of pure 
potash. Hence it is evident that 45 grammes, or 1 ounce, 
of these branches contain as much potash as 1000g;rammes 
(1 litre) of wine. But from ten to twenty times this quan- 
tity of branches are yearly taken from the above extent 
of surface. 

In the vicinity of Johannisberg, Rudesheim, and l^udes- 
heim, new vines are not planted after the rooting out of the 
old stocks, until the land has lain for five or six years in 
barley and esparsette or lucern ; in the sixth year the 
young sto«ks are planted, but not manured till the ninth. 



ON THE BIANURING OF THE SOIL IN VINEYARDS.* 

"In reference to an article in your paper. No. 7, 1838, 
and No. 29, 1839, I cannot omit the opportunity of again 
calling the public attention to the fact, that nothing more is 
necessary for the manure of a vineyard than the branches 
which are cut from the vines themselves. 

" My vineyard has been manured in this way for eight 
years, without receiving any other kind of manure, and yet 
more beautiful and richly laden vines could scarcely be 
pointed out. I formerly followed the method usually prac- 
tised in this district, and was obliged in consequence to 
purchase manure to a large amount. This is now entirely 
saved, and my land is in excellent condition. 

"When I see the fatiguing labor used in the manuring 
of vineyards, — horses and men toiling up the mountains 
with unnecessary materiaJs, — I feel inclined to say to all. 
Come to my vineyard and see how a bountiful Creator has 
provided that vines shall manure themselves, like the trees 
in a forest, and even better than they ! The foliage falls 
from trees in a forest, only when they are withered, and 
they lie for years before they decay ; but the branches are 
pruned from the vine in the end of July or beginning of 
August whilst still fresh and moist. If they are then cut 
into small pieces and mixed with the earth, they undergo 

• Slightly abridged from an article by M. Krebs of Seeheim, in the 
" Zcitsclirift fur die lamlwirlhschafdichen Vereine des Grosherzogthums 
Hcssenr No. 2d, July 9, 1840. 



ON THE MANURING OF THE SOIL IN VINEYARDS. 255 

putrefaction so completely, that, as I have learned by ex- 
perience, at the end of four weeks not the smallest trace 
of them can be found." 



" Rebiarks of the Editor. — We find the following 
notices of the same fact in Henderson's ' Geschiclile der 
Weine der alien und neiien Zeit ' : — 

" 'The best manure for vines is the branches pruned 
from the vines themselves, cut into small pieces, and im- 
mediately mixed with the soil.' 

"These branches were used as manure long since in the 
Bergstrasse. M. Frauenfelder says :* 

" ' I remember that twenty years ago, a man called 
Peter Miiller had a vineyard here, which he manured with 
the branches pruned from the vines, and continued this 
practice for thirty years. His way of applying them was 
to hoe them into the soil after having cut them into small 
pieces. 

" ' His vineyard was always in a thriving condition ; so 
much so, indeed, that the peasants here speak of it to this 
day, wondering that old Miiller had so good a vineyard, 
and yet used no manure.' 

"Lastly, Wilhelm Ruf of Schriesheim writes : 

" ' For the last ten years I have been unable to place 
dung on my vineyard, because I am poor and can buy 
none. But I was very unwilling to allow my vines to de- 
cay, as they are my only source of support in my old age; 
and I often walked very anxiously amongst them, without 
knowing what I should do. At last my necessities became 
greater, which made me more attentive, so that 1 remarked 
that the grass was longer on some spots where the branch- 
es of the vine fell than on those on which there were none. 
So I thought upon the matter, and then said to myself: If 
these branches can make the grass large, strong, and 
green, they must also be able to make my plants grow bet- 
ter, and become strong and green. I dug therefore my 
vineyard as deep as if I would put dung into it, and cut the 
branches into pieces, placing them in the holes and cover- 
ing them with earth. In a year I had the very great ^tis- 
faction to see my barren vineyard become quite beautiful. 
This plan I continued every year, and now my vines grow 

* Badlsches lajidwirthschaftliches Wochenblatt, v. 1834, S. 52 and 79. 



256 APPENDIX TO PAKT I. 

splendidly, and remain the whole summer green, even in 
the greatest heat. 

" ' All my neighbors wonder very much how my vine- 
yard is so rich, and that I obtain so many grapes from it, 
and yet they all know that I have put no dung upon it for 
ten years.' "* 



ROOT SECRETIONS. 

It shoald be stated, that the accuracy of the experiments 
of Macaire-Princep adduced by the author, page 164, is 
not generally admitted. Other chemists have been unable 
to obtain similar results, or if they do are inchned to as- 
cribe them to injury of the roots of the plants examined. 
Professor Lindley in his notice of Liebig's work has re- 
marked, that he has no fixed opinion on the subject, it 
being a question of facts and not of induction. Admitting 
root secretions, he nevertheless does not deem it necessary 
to look to the roots for these excretions, when we have so 
many proofs of their constant occurrence in other parts of 
a plant, as in the oily, resinous, waxy, acid, and acrid mat- 
ter, from various parts of their surface, and in the peculiar 
substances lodged in the hollows of their stems or elsewhere, 
such as Tabasheer, in the bamboo. These are thought to 
be instances, "sufficient to satisfy the necessity of excre- 
tions occurring, and to render it superfluous to look to the 
roots for further aid in this particular." 

The subject of excretion is one of great interest, and 
deserving of further examination. Seveial botanists have 
recently stated what are deemed fatal objections to the cor- 
rectness of De Candolle's conclusions from Macaire's ex- 
periments. It is maintained, that the process of excretion 
from the roots of plants is not analogous to that of excretion 
in animals ; that the deposits consist of materials which 
were in superabundance in the system of the plant, and 
that the reason why the same species of plants do not grow 
one after the other, is, that the first exhausted the soil of 
the materials necessary for the nourishment of the next. 
In some parts of the world, wheat crops are said to have 
been obtained fifty years in succession, where the supply 
of nutriment was sufficient. The application of the recent 
discovery of the means of coloring the wood of trees by 

* The e.'cperiment has been made here with success — fV, 



ROOT SECRETIONS. 257 

introducing coloring matters into their trunks, is i-eported 
to have shown that the coloring matters are thrown off 
from the roots, and plants growing near them have been 
poisoned, although the plant colored continued to grow. 
Report of British Association Meeting, August, 1841. 

A series of experiments on this subject has been going 
on during live years in the Botanic Garden, Oxford, under 
the direction of Professor Daubeny. His object is to as- 
certain, " in the first place, how many successive years the 
soil may admit of the growth of the same crop, and, if it 
becomes deteriorated, at what rate the decrease of produce 
may proceed ; and, in the second place, what kind of vege- 
tables will afterwards thrive best in soil, which, with refer- 
ence to this particular crop, has become damaged, or 
effete. 

" With a view to determine this, I have set apart, in one 
portion of our Botanical Garden, a number of distinct plots 
of ground, of known size, and uniform as to quality. 

" These were in the first instance enriched with an equal 
amount of manure, and brought, as nearly as could be 
done, in every respect into a similar condition. 

"Fifteen of these beds are planted year after year, with- 
out intermission, with the following crops : viz. potatoes, 
turnips, barley, oats, poppies {Papaver samniferum) , buck- 
wheat, tobacco [JYicoliana ruslica), flax, hemp, endive, 
clover {Trifolium pratense), mint {Madlia viridis), beans, 
parsley, and beet. 

"The remaining fifteen beds receive in turn the same 
crops, but each year a different one is introduced ; so that 
by comparing the amount of produce obtained each year 
fi'om the first and second class of beds, — those in which 
the crop is permanent, and those in which it is made to 
shift about, — we may be enabled to learn, how much of 
any actual diminution ought to be attributed to the season, 
and how much to a deterioration or exhaustion of the soil. 

"As it is scarcely five years since the experiments were 
commenced, the progress made has not yet been sufficient 
to render the results worth quoting ; but should life and 
leisure be allowed me for bringino: them to a conclusion, 
I trust some inferences may herea{lt«r be deduced of utility 
to future husbandmen ; although I should be far more 
sanguine with respect to the benefit that would accrue, if a 
piece of ground of greater extent were set apart for such 
experiments, as, under the auspices of any of our great 
Agricultural Societies, it might not be difficult to effect. 
22* 



258 APPENDIX TO PART I. 

"Should Science, indeed, succeed in settling the true 
cause of the deterioration of crops, and tiie most advan- 
tageous order of their succession, it is unnecessary for me 
to point out how important a boon she would confer upon 
the agriculturist. 

"So extremely various, indeed, are the systems upon 
which the rotation is carried on in different countries, that 
no fixed principle would appear to regulate them, and the 
whole may be considered, as being founded much more 
upon the authority of long usage and tradition, than upon 
any actual comparison of the relative advantages of those 
resorted to in various places. 

"This inquiry may therefore be pointed out, as being 
one of those lines of investigation, in prosecuting wifPbh 
the scientific chemist may be expected to benefit the prac- 
tical farmer." 



PEAT COMPOST. 
(See p. 118, and 185) 

According to the statement of Messrs. Phinney and 
Haggerston, as contained in the Report on the Geological and 
Agricultural Survey of Rhode Island, by Dr. C. T. Jack- 
son, a compost made of three parts of peat and one of sta- 
ble manure, is equal in value to its bulk of clean stable 
dung, and is more permanent in its effects. 

Dr. Jackson deems it essential that animal matters of 
some kind should be mixed with the peat, to aid the de- 
composition and produce the requisite gases. Lime de- 
composes the peat, neutralizes the acids, and disengages 
the ammonia. The peat absorbs the ammonia, and be- 
comes in part soluble in water. The soluble matter, ac- 
cording to Dr. Jackson, is the apocrenate of ammonia ; 
crenate of ammonia and crenate of lime being also dis- 
solved. With an excess of animal matter and lime, free 
carbonate of ammonia is formed. 

The peat should be laid down in layers with barn-yard 
manure, night-soil, dead fish, or any other animal matter, 
and then each layer strewed with lime. In Dr. Jackson's 
Report, he has presented highly valuable results from the 
use of this compost, which deserve the attention of every 
agriculturist. He gives the following details of the man- 



PEAT COMPOST. 259 

ner in which the compost was prepared upon the farm of 
Mr. Sandford, near the village of VVickford in North King- 
ston. " In the corner of the field a cleared and level spot 
was rolled down smooth and hard, and the swamp muck 
was spread upon it, forming a bed eight feet wide, about 
fifteen or twenty feet long, and nine inches thick. For 
every wagon load of the muck one barrel offish was added, 
and the fish were spread on the surface of the muck, and 
allowed to become putrescent. The moment they began to 
decompose, he again covered them with peat, and a renew- 
ed layer of fish was spread and covered in the same man- 
ner. The fermentation was allowed to proceed for two or 
three weeks, when the compost was found to have become 
fit for the land. To this he was advised to add lime in the 
proportion of one cask to each load of compost early in 
the spring, which it was supposed would complete the de- 
composition in two or three weeks. Such a heap should 
be rounded up and covered, so as to prevent the rain wash- 
ing out the valuable salts, that form in it. And in case of 
the escape of much ammonia, more swamp muck or peat 
should be spread upon the heap, for the purpose of absorb- 
ing it." Dr. Jackson is of opinion, that the phosphoric acid 
of the peat and animal matter would convert the lime into 
a phosphate, and thus approximate it very closely to bone 
manure. — Report, p. 170. 

Any refuse animal matter can be, of course, employed 
in a similar manner. " The carcass of a dead horse, which 
is often suffered to pollute the air by its noxious effluvia, 
has been happily employed in decompo-sing 20 tons of peat 
earth, and transforming it into the most enriching manure." 
— Young's Lelttrs ofAgricoln, Letter 25, p. 238.* 

Night soil may be composted with peat with great advan- 
tage, sufiicient lime being added to deprive it of odor; large 
quantities of ammonia are given off and absorbed. t 

Appended to Dr. Jackson's Report will be found a letter 

* In a Report on a ReSxamination of tlic Geology of Massachvsetts, 
1838, Dr. Dana particularly notices the evolution of ammonia from fer- 
menting dung, and supposes that the ammonia conibines with geine to 
form a soluble com pound. See Note to page 83 of the Report. 

1 jXiir/tt-SolL The quantity of night-soil collected and removed from 
the city of IJoston annually, is about four hundred thousand square feet. 
It is used by cultivators in the ininiediale vicinity, being composted 
with soil, linie, peat, &c. Large quantities of animal matter from 
slaughter-houses, and other sources, are also made use of The heaps 
are left exposed, uncovered to the air, and the value of the compost is 
consequently greatly diminished. See page 199. 



260 APPENDIX TO PART I. 

from E. Phinney, Esq., of Lexington, well known as one 
of the most skilful agriculturists, "On the reclaiming of peat 
bogs and the employment of peat as manure." 



SOURCE OF THE CARBON OF PLANTS. (fROBI DAXJBENY's 

LECTURES ON AGRICULTURE, 1841.) 

(See Chapter II.) 

" llNTiiTwithin the last century, it would have been taken 
for granted, that the soil was the source trom whence pro- 
ceeded all the solid matter at least which entered into the 
constitution of a plant, and there were several circumstan- 
ces which tended to countenance such an opinion. No 
plants, it was observed, would continue long to thrive in 
earth unmixed with some proportion of vegetable mould, 
and the fertility of the latter is greatly enhanced by the 
addition of animal or vegetable matter, in that state of de- 
cay, in which it becomes soluble in water, and therefore 
fitted to obtain admission into the vessels of plants. 

"Hence, when Priestley had demonstrated, that leaves 
decompose the carbonic acid of the atmosphere, giving out 
its oxygen and assimilating its carbon, the doctrine alluded 
to still to a certain extent maintained its ground; and it was 
even questioned by Ellis and others, whether in fact, if we 
were to strike the balance between the opposite influence 
of a plant during the day and the night, as much carbonic 
acid might not be exhaled by it at one period, as had been 
decomposed at another. 

" I was therefore induced myself to undei'take some ex- 
periments,* the results of which appear to establish, that 
plants, even in a confined atmosphere, do in reality add a 
great deal more oxygen to the air than they abstract from 
it, whilst tiie amount of carbonic acid which mav be intro- 
duced undergoes at the same time a corresponding dimi- 
nution. 

"This Cifect I even found to take place in diffiised light, 
as well as under the direct influence of the solar rays, and 
to be no less common in aquatic than in terrestrial plants. 

" I also showed, that when a branch loaded with flowers, 
as well as with leaves, was introduced into ajar containing 

" * See PJiilosnphical Transactions for 1836." 



DAUBENY ON THE CARBON OF PLANTS. 261 

a certain proportion of carbonic acid, the balance still con- 
tinued to be in favor of the purifying influence of the veg- 
etable. 

"The apparatus I made use of consisted of a large bell- 
glass jar, containing in one case 600, in another 800 cubic 
inches of air,* and suspended by pulleys. Its edges dipped 
into quicksilver, contained in a double iron cylinder of cor- 
responding dimensions to the jar, which, being closed at 
bottom, constituted a well of about six inches in depth, cal- 
culated to receive a fluid, and to admit of the glass vessel 
moving freely in it. The inner margin of this hollow cylin- 
der was cemented air-tight, according as circumstances re- 
quired, either to a plate of iron, or to a pot of the same 
material upon or in which the plant operated on might be 
placed ; and the jar was then let down upon it, until its 
edges were sunk a little beneath the surface of the mercury. 

"Thus all communication with the external atmosphere 
was cut off", and the effect of the plant upon the air inclosed 
in the jar was readily measured, by simply pressing down 
the latter, and thus expelling a portion of its contents 
through a tube, communicating with its interior, and intro- 
duced at its outer extremity under a pneumatic trough, 
wherein the air might be collected and examined. By con- 
necting this extremity with a vessel containing a measured 
quantity of carbonic acid, and raising the jar a little in the 
well of mercury, it was easy to draw in any proportion of 
that gas, with which it was thought proper that the plant 
should be supplied. A portion of the air was always tested, 
immediately after the introduction of every fresh portion 
of carbonic acid, and again after an interval of some hours, 
and the proportion of this gas and of o.xygen present was 
each time carefully registered. The amount of carbonic 
acid was determined by a solution of potass, that of oxygen 
by the rapid combustion of phosphorus with a portion of it 
introduced into a bent tube. 

" Such was the mode of procedure, when an entire plant 
became the subject of experiment ; but some of the most 
satisfactory trials were with branches of certain shrubs, 
them-^elves too large to be admitted under the jar. These 
branches, without being detached from the parent trunk, 
were introduced through a hole in the centre of two corre- 
sponding semicircular plates of iron, which were cemented 
air-tight, to the inner margin of the iron cylinder on the 

" • Larsrer jars, containing from 1200 to 1300 cubic inches were lat- 
terly employed." 



262 APPENDIX TO PART I. 

one hand, and to the stem of the branch on the other. In 
this manner, when the jar came to be placed over them, 
and to dip beneath the surface of the mercury, the external 
air was as effectually excluded, as when the whole of the 
plant had been enclosed. 

"The results of several experiments conducted after 
this plan are given in a tabular form in the Memoir ; but 
it may be sufficient here to specify one of the most satis- 
factory of those undertaken. In this case the jar itself 
contained about 600 cubic inches of air, and the plant ex- 
perimented on was the common lilac {syringa vulgaris). 
The proportion of carbonic acid in the jar was each morn- 
ing made equivalent to five or six per cent, by additions 
through the tube. 

"The first day no great alteration in the air was detect- 
ed, but on the second day, by eight in the evening, the 
oxygen had risen to 26 "5 per cent. In the morning it had 
sunk to 26 0, but by two P. M. it had again risen to no less 
than 29-75, and by sunset it had reached 300 per cent. At 
night it sunk one half per cent. ; but the effect during the 
following day was not estimated, as the sickly appearance 
which the plant now began to assume induced me to sus- 
pend the experiment. 

" In a second trial, however, the branch of a healthy 
lilac growing in the garden was introduced into the same 
jar, where it was suffered to remain until its leaves became 
entirely withered. 

"The first day the increase of oxygen in the jar was no 
more than 025 per cent., but on the second it rose to 25-0. 
At night it sunk to nearly 220 per cent., but the next 
evening it had again risen to 27 0. This was the maximum 
of its increase, for at night it sunk to 26 0. and in the 
morning exhibited signs of incipient decay. Accordingly 
in the evening the oxygen amounted only to 26-5 ; the 
next evening to 255 ; the following one to 24-75 ; and the 
one next succeeding it had fallen to the point at which it 
stood at the commencement, or to 21-0 per cent. 

"The reason of this decrease was, however, very mani- 
fest from the decay and falling off of the leaves ; so that 
this circumstance does not invalidate the conclusion which 
the preceding experiments concur in establishing, namely, 
that in fine weather a plant, so long at least as it continues 
healthy, adds considerably to the oxygen of the air when 
carbonic acid is freely supplied. 

" In the last instance quoted, the exposed surface of all 



DAUBENY ON THE HYDROGEN OF PLANTS. 263 

the leaves enclosed in the jar, which were about fifty in 
number, was calculated at not more than 300 square inches, 
and yet there must have been added to the air of the jar as 
much as 26 cubic inches of oxygen, in consequence of 
the action of this surface upon the carbonic acid introduced. 

" But there is reason to believe, that even under the cir- 
cumstances above stated (which appear more favorable to 
the due performance of the functions of life than those to 
which Mr. Ellis's plants were subjected), the amount of 
oxygen evolved was much smaller than it would have been 
in the open air, for I have succeeded, by introducing sev- 
eral plants into the same jar of air in pretty quick succes- 
sion, in raising the amount of o.\ygen contained from twen- 
ty-one to thirty-nine per cent., and probably had not even 
then attained the limit to which the increase of this con- 
stituent might have been brought. 

" How great then must be the effect of an entire tree in 
the open air under favorable circumstances ! and we must 
recollect that, cceleris paribus, the circumstances will be 
favorable to the exertion of the vital energies of the plant, 
within certain limits at least, in proportion as animal respi- 
ration and animal putrefaction furnish to it a supply of car- 
bonic acid. 

"These experiments were published in the Philosophical 
Transactions for 1836, and have been noticed in Dr. Lind- 
iey's popular Introduction to Botany ; neither am I aware 
that the deductions which were drawn from them have any- 
where been disputed." 



Source of the Hydrogen of Plants ; from Dauhemfs Lectures. 
(See Chapter IV.) 

"It would seem, I think, from the late important re- 
searches of M Payen, that the decomposition of water 
commences subsequently to that of carbonic acid, whether 
it be, that the former process requires a greater develop- 
ment and energy in the vegetable functions, or that it takes 
place in organs of a different description and of later 
growth. 

" M. Payen seems to have established, that under the 
general term of ligneous fibre, or lignin, we have hitherto 
confounded at least two distinct substances, namely, that 
which constitutes the walls of the cells, and that which, by 
being deposited afterwards on the surfaces of the latter, 



264 



APPENDIX TO PART I. 



imparts to them the solidity of texture which woody fibre 
possesses. 

"He has succeeded in isolating the two by chemical 
means, and has found, that whilst the cellular matter has 
exactly the same composition as starch, being composed 
of 449 carbon, 6"1 hydrogen, 49 oxygen, or 44'9 carbon 
and 55' 1 of water; the incrusting matter afterwards formed 
consists of 53-76 carbon, 40.2 oxygen, and 6 of hydrogen, 
or of 53-76 carbon, 45-2 of water, and 1 of hydrogen.* 

"The composition of the Jigneous matter of different 
kinds of wood will therefore vary according to the relative 
proportionrof these two ingredients, as is shown in the 
following table of M. Payen : — 



Ligneous Bodies. 
Incrusting matter of the wood 


Carbon. 


Hydrogen. 


Oxygen. 


Incrusting 
matter. 

190 


53-76 


6-O0 


40 20 


Wood of Saint Lucia 


52-!i0 


G-07 


4103 


90 


Ebony .... 


^2-65 


6 00 


41-15 


89 


Walnut .... 


51 92 


5-9(i 


42 12 


82 


Oak 


50-00 


6 20 


43-80 


61 


Ditto according to Gay-Lus- 










sac, and Thenard 


51-J5 


5-H2 


42-73 




Beech .... 


49 2^ 


6-10 


44-()o 


52 


Celhilar matter . 


44-90 


6-10 


49 00 


00 



"This then proves, that, in the formation of the matter 
which incrusts and fortifies the walls of the cellular tissue 
in wood, though not in that of the cellular tissue itself, a 
decomposition of water must have taken place ; since the 
1 per cent, of hydrogen which Payen has found in excess, 
can only have arisen in this manner. 

"This increase of hydrogen becomes still greater, when, 
in the progress of vegetation, the plant begins to secrete 
oils, camphors, and other analogous bodies, products, 
which, it is to be remarked, abound most within the tropics, 
■where the light of the sun is most intense. 

"Hence the decomposition of water, no less than that 
of carbonic acid, seems due to solar influence, and accord- 
ingly, the greater sweetness of subacid fruits, in a warm 
than in a cold summer, arises from the transformation of 
a larger amount of tartaric or other vegetable acids into 
sugar, owing to that separation of oxygen from the former 
which is accomplished by the agency of light. 

"The process of assimilation of plants in its most simple 



" * Payen has since stated, that this incrusting matter probably con- 
sists of two or three different principles." 



DAUBENY ON THE NITROGEN OF PLANTS. 265 

form may therefore be stated, as consisting in the extrica- 
tion of hydrogen from water, and of carbon from carbonic 
acid, in consequence of which one of three things must 
happen, — either all the oxygen of the water and of the 
carbonic acid are separated, as in those bodies which, like 
caoutchouc, volatile oils, &c., consist of nothing else but 
carbon and hydrogen ; or, secondly, only a part of it is 
exhaled, as in the case of the incrusting matter of wood, 
and in sugar ; or, thirdly, that belonging to the carbonic 
acid alone is decomposed, whilst the water remains, as in 
starch and cellular tissue." 



Dependence of the nutritive Qualities of Plants on their JS'itro- 
gen; from Daubeny's Lectures. 

(See page 139.) 

"The dependence of the nutritive qualities of various 
articles of food upon the proportion of nitrogen is well 
shown in a recent memoir of Monsieur Boussingault,* who 
gives, on the authority of the celebrated agriculturist Von 
Thaer, a scale of the relative degree of nutriment afforded 
by various plants to cattle, and then places by the side of it 
a statement of the proportion of azote present in them, from 
which it appears, that the nutritious quality of each bears 
a pretty constant ratio to the quantity of nitrogen they 
contain. 

"This may be seen by the following table : 

Equiv. 

Ordinary hay . . 100 its azote being 0-0118 

Red Clover . . . 90 . . . 0-0176 

Beans .... 83 . . . 0-0141 

Wheat-straw . . . 400 . . . 0-0020 

Potatoes . . . 200 . . . 0-0037 

Beet .... 397 .. . 0-0026 

Maize .... 59 . . . 0-1)164 

Barley . . . . 54 . . . 0-0176 

Wheat .... 27 . . . 0*0213 

"When we reflect, indeed, that animal matter, which so 
abounds in nitrogen, is nevertheless derived, either directly 
or indirectly, from vegetable, it follows, as a necessary 
consequence, that existence can only be maintained by the 
aid of those principles in plants, which contain a certain 
proportion of the element alluded to. 

"* Annales de Chimie, Vol. LXIII." 

23 



266 APPENDIX TO PART I. 

"And this has been shown by the experiments of Ma- 
gendie upon dogs, which were fed on sugar, starch, gum, 
and other substances destitute of nitrogen, and in a very 
short time pined away and died." 

Difference between different Plants in their power of decom- 
posing Ammonia; from Daubeny's Lectures, 

(See Chapter V.) 

"It maybe inferred, from some experiments made by 
Boussin^ult, that a great difference exists between plants 
in their power of assimilating nitrogen, and to this differ- 
ence that chemist is disposed to attribute the advantage of 
alternately growing wliat are called fallow crops, for the 
purpose of refreshing the soil. 

"'During germination,' he remarks, 'the quantity of 
azote which seeds contain appears to be on the increase, 
but there is this curious difference between different kinds, 
that whilst those of leguminous plants, sown in pure earth 
and moistened with nothing but distilled water, obtained an 
increase of nitrogen which the atmosphere alone could 
have afforded, those of barley and other cerealia remained 
in that respect stationary, unless manure were afforded.' 

"Boussingault also shows in a subsequent memoir, that 
peas, clover, and other legumes absorb azote, even when 
planted in a soil that contains no decomposing animal or 
vegetable matter, but that the cerealia, although if so 
placed, they may grow, do not appear to secrete this- 
principle. 

"Boussingault, however, does not go so far as to main- 
tain, that the latter in no stage of their existence are capa- 
ble of discharging this function, but only that the plant 
must have already arrived at a higher state of vigor, in 
order to derive its supply from such a source. 

"It is on the same principle, that although the animal 
in general obtains its food from the various organic bodies 
on which he subsists, yet that in an early stage of existence, 
before his organs are fitted for undergoing the labor of 
assimilating such materials, nature has provided him in his 
mother's milk with aliment already almost elaborated. 

"It is thus, too, that in the seed the embryo is sur- 
rounded with a mass of albumen, from which it derives its 
support, until its roots become sufficiently vigorous to 
extract nourishment from the ground. 

"Hence it becomes in most cases necessary, that crops 



DAUBENY ON AMMONIA OF PLANTS. 267 

cultivated as articles of food should have access to vege- 
table or animal manure from which they may derive their 
azote, but as this supply would soon be exhausted, were it 
not at the same time regenerated from the atmosphere, we 
see the advantage of intercalating a green fallow crop 
ploughed into the ground with others ; as leguminous 
plants, according to the experiments of Boussingault, have 
the greatest power of absorbing nitrogen from the air. 

"On the same principle this chemist suggests the intro- 
duction of the Jerusalem artichoke into light soils, which, 
owing to the entire absence of mould, appear irreclaimably 
barren; this vegetable, the tubers of which afford nourish- 
ment to cattle almost equal to potatoes, having great power 
of absorbing both carbon and nitrogen from the air, and 
thus by degrees generating a certain amount of soil* 

" I have seen this vegetable very commonly cultivated 
for the use of cattle, in the light lands of the Grand Duchy 
of Baden, and in certain parts of Alsace. 

" But if it be true, as Liebig has endeavored to establish, 
that plants obtain every thing except their alkalies and 
earthy constituents from the atmosphere, what, it may be 
asked, becomes of the theory that attributes the unfitness 
of a soil for yielding several successive crops of the same 
plant to the excretions given out by its roots } 

"For if plants receive the whole of their volatilizable 
ingredients from the atmosphere, these excrementitious 
matters, being composed chiefly of carbon, hydrogen, and 
oxygen, will not be absorbed, and therefore cannot affect 
the succeeding vegetation. 

"The above inference would seem unavoidable, if it 
were considered absolutely proved, that nothing but the 
fixed ingredients of a plant were derived from the earth, 
but this is not fully established, even with respect to the 
humus, much less with respect to the more soluble matters 
which the soil contains. 

"These latter, there seems no reason for doubting, may 
be taken up by the spongioles of the roots dissolved in 

" * It is to be observed, that Boussingault attributes to plants the 
power of absorbing nitrogen from the air, but he alleges no proof that 
they have that power, and his results may be just as well explained 
by supposing them to have different powers of absorbing ammonia. 
It is to be remarked, that the helianthus tuberosus belongs to a tribe 
of plants remarkable for their power of absorbing and exhaling water, 
and hence it is evident, that they will be brouo-ht into contact within a 
given time with a larger amount of ammonia, than other plants, which 
possess a less degree of energy in that respect." 



268 APPENDIX TO P.^T I. 

water, together with the alkaline and earthy ingredients 
which are derived from the soil, nor am 1 aware of any 
proof that they may not likewise be assimilated when so 
introduced. 

" The theory of M. DecandoUe, therefore, is not affected 
by the above experiments, but must rest on its own merits, 
and continue to afford a subject for inquiry to the scientific 
agriculturist." 



PradicsU Inferences. From Dr. Daubeny's Lectures on 
Jigricullure , delivered at Oxford, 1841. 

"The first inference that may be drawn, relates to the 
utility of diligent and frequent tillage, in order to favor the 
disintegration of the soil, and the free admission to it of 
oxygen and of water. 

"Unless the former take place, no fresh alkali can be 
extracted from the subjacent rock by the action of water 
upon it ; unless the latter be brought about in a sufficient 
degree, the humus excluded from air cannot undergo that 
process of eremacausis, or gradual combustion, on which 
its influence upon the nutrition of plants has already been 
shown to depend. 

"Hence, in ancient times, the importance attached to 
those operations which had this object for their aim, — 

" ' Quid est agrum bene colere ? ' asked Cato. ' Bene arare. Quid 
secundum? Arare. Quidtertium? Stercorare.' 

Thus ploughing was regarded the most important process 
in agriculture, after which, though at a long interval, came 
manuring. 

"The design, therefore, of the agriculturist is, to reduce 
the soil to that loose and crumbling condition, in which it 
becomes entirely pervious to air and moisture, imparting to 
it the quality which the ancients denominated putre. 

" ' Et cui putre solum, (namque hoc imitamur arando,) 
Optima frumentis.' 

"Hence the superiority of spade husbandry over the 
plough, if the expense of the labor be not taken into the 
account ; hence the fertility of the small farms of the ancient 
Romans, notwithstanding their rude methods and their 
deficiency of skill ; hence the fine condition of those tracts 
of land, which are subjected to the unremitting manual ex- 
ertions of societies of men like the Trappists, whose mis- 



PRACTICAL INFERENCES. 269 

taken views of religion have led them into that entire iso- 
lation from human society, under which even the severest 
physical toil becomes itself a relief. 

"The same principle explains in some degree the utility 
of subsoil-ploughing, which, by bringing up to the surface 
a portion of earth previously out of the reach of those in- 
fluences which tend to cause its disintegration, extracts 
from it the alkaline and other ingredients required by the 
plant for its subsistence. 

" It is found advantageous, in the first instance, merely 
to break and pulverize the subsoil to a depth of eighteen 
or twenty inches, without bringing it to the surface, and 
only after a lapse of four or five years to mix it with the 
vegetable mould above, a practice, the utility of which de- 
pends, not only on the mechanical condition of the land 
being rendered more favorable to culture in consequence 
of its becoming more friable, but likewise, probably, owing 
to the chemical decomposition of its component parts having 
taken place more completely. 

" Other circumstances, such as its influence on the drain- 
age of the land, will no doubt cooperate in producing the 
benefit which often results from the practice of subsoiling ; 
but that the cause pointed out really contributes to its 
efficacy, may be inferred from a fact attested by many ex- 
perienced agriculturists,* namely, that those soils are most 
benefited by subsoil-ploughing, which can be rendered 
thereby more pervious to moisture, and consequently to 
air ; whilst those which contain too large a percentage of 
clay to be affected in this manner by the process, derive 
no advantage from it. 

"But it must not be forgotten, that the utmost pains be- 
stowed upon its elaboration cannot generate any new prin- 
ciples, but only act, by enabling the soil to impart more 
readily to the crop those which it already possesses. 

" This obvious truth will explain the cause of the disap- 
pointment felt by farmers, at finding, that after a certain 
time, the most dilio-ent tillage no longer affords them the 
same returns as it did at first. 

"It it said, that Jethro Tull, who first proved the ad- 
vantages of deepening and pulverizing soils, was neverthe- 
less obliged at length to admit, that at each repetition of 
the experiment the success was less decided, unless manure 
were at the same time applied. Judicious tillage, in short, 

" • See English .Agricultural Journal, No. 5, p. 32." 

23* 



270 APPENDIX TO PART I. 

like the use of machinery in the arts, does not create any 
new power, but only tends to render more available those 
already latent in the earth. 

"It was not therefore without reason, that Cato, after, 
as we have seen, pronouncing, that the first, and the second 
thing in agriculture, is to plough, adds, that the third is to 
manure, for what is this but the art of providing for the in- 
tended crop an adequate supply of those ingredients which 
enter into its composition ? 

"The principles therefore which have been laid down, 
whilst th&y will serve to guide the husbandman in the se- 
lection of his fertilizers, may also explain the different re- 
sults that are obtained from the use of the same kind of 
mineral manure in different soils. 

"Among those which have excited the greatest interest 
within the last few years, may be mentioned the nitrates of 
potass, and of soda. 

"The former, commonly called saltpetre, is produced 
spontaneously in most parts of the world, and especially in 
hot countries, in consequence of animal and vegetable 
decomposition conducted under particular conditions, and 
accordingly it has been introduced into agriculture from an 
early period.* 

"The latter, sometimes distinguished from its crystalline 
form, as cubic nitre, is met with in large quantities in Peru, 
fourteen leagues from the port of Iquicque, where, ac- 
cording to Mr. Darwin, ■(■ it forms a stratum two or three 
feet thick, lying close beneath the surface, and following 
the margin of a grand basin or plain, elevated 3300 feet 
above the level of the Pacific, but which, nevertheless, 
appears evidently to have been at one time a lake, or in- 
land sea. 

"The price of the salt at the ship's side in 1835, at the 
time Mr. Darwin visited the spot, was fourteen shillings a 
cwt., the grand item of expense being its transport to the 
coast. J 

" * Where the price operates as an objection to its use, the method 
of forming artificial nitre-beds, by mixing together vegetable and ani- 
mal matters in a state of decomposition with calcareous earth, may be 
economically adopted. See Cuthbert Johnson, on Saltpetre and Ni- 
trate of Soda, Ridgway, 1840." 

" t See Darwin's Journal, in Voyage of the Beagle." 
i Mr. J. H. Blake of Boston, who recently visited Peru, informs me, 
that the cost of the nitrate of soda was ,$2.50 per quintal, and that it 
could be obtained here at from 4.^ to 5 cents per lb. The crude nitrate,, 
containing from 70 to 80 per cent, of the pure salt, might be obtained 
here at 2^ cents per lb — JV. 



PRACTICAL INFERENCES. 



271 



"These particulars are perhaps not unimportant, as they 
may serve to show that an ahnost unlimited supply of both 
these salts may be calculated upon, and, in the case of the 
nitrate of soda, that its price might be kept down, rather 
than enhanced, by an increased demand. 

"That, however, with which the agriculturist is most 
concerned, is to determine the relative value of these salts 
as manures, and to discriminate the kind of land to which 
either or both are beneficial. 

" Now, it is remarkable, that the nitrates, whilst they 
have in some cases occasioned a wonderful increase of pro- 
duce, in others have appeared of little service, and also 
that, whereas on certain land both were equally efficacious, 
on a different description of soil, the one has answered, 
whilst the other failed. 

" For a great deal of interesting information on this sub- 
ject, I may refer to the Journal of the Royal Agricultural 
Society of England, — its last number* more especially: 
on the present occasion I shall confine myself to noticing 
the communication of Mr. Hyett, of Painswick, as one, 
which probably points to the true cause of the advantage 
derived from the employment of these salts. 

"Mr. Hyett's experiments were made upon the stone or 
cornbrash of Gloucestershire, a coarse and impure oolitic 
limestone, which had been drilled with white Sicilian wheat 
in the autumn. 

" Nitrate of soda, at the rate of 1 cwt. to the acre, was 
on the 21st of April, sown and hoed in over all the field, 
excepting two square portions, which were staked out, and 
left unnitrated. 

"On the 1 6th of May the effect of the salt was per- 
ceived, by the dark green color of the plants. 

" The results of the harvest were as follows : 



Produce. 


i\Ieasure per acre. 
Without nitrate. | With nitrate. 


Value per acre. 
Excess. 


Corn clean . . 

tail . . . 

total . . 


Bu. Pks. Pts. 

30. 2. 11 

2. 3. 11 


Bu. Pks. Pts. 

37. 3. 4 

5. 3. 7 


Bu. Pka. Pts. 
7. 0. 9 
2. 3. 12 


33. 2. 6 43. 2. 11 


10. 0. 5 


1 Weight. 1 Per acre. | | 


Straw 


T. Cwt. qrs. lbs. 1 T. Cwt. qrs. lbs. 
1. 3. 1. 21 jl. 11. 2. 3 


T. Cwt. qrs. lbs. 
0. 8. 0. 10 



"From these data Mr. Hyett calculates, that the in- 
creased value of the produce, arising from the use of the 

"* For January, 1841." 



272 



APPENDIX TO PART I. 



nitrate of soda, gives a profit of 2/. 17s. 2d. per acre, after 
deducting I/. 3s. Od. for the value of the salt employed. 

"But not only does the nitrate increase the quantity of 
the grain, but it tends to augment those ingredients, which 
contain the largest amount of nitrogen, and consequently 
afford the greatest degree of nutriment, namely, the gluten 
and albumen. 

" This is shown, by the analysis of the nitrated, and non- 
nitrated wheat, made by a chemist at his request, the re- 
sults of which were as follows : 



_» 








Wheat on which the 


Wheat on which no 




nitrate was used, gave 


nitrate was us>3d, gave 


Bran 


25000 


24-000 


Gluten 


23 250„ 


19000 


Starch 


49'50(r 


55-500 


Albumen 


1-375 


-6-25 


Extract 


•375 


•250 


Loss and water . . 


•5 


•628 


100- parts. 


100- parts. 



"Thus it is seen, that in the nitrated wheat there was 
4'25 per cent, more gluten, and 075 more albumen, than 
in the non-nitrated sample. 

" Considering, then, that these constituents contain nearly 
16 per cent, of nitrogen, we are justified perhaps in at- 
tributing their increase to the decomposition of the nitric 
acid present in the salt, and the consequent supply of nitro- 
gen in greater abundance than is naturally present in the 
soil. 

"And if such be the mode of its operation, it may be 
possible to explain why these salts should appear so capri- 
cious in their eftects on the different kinds of land to which 
they have been applied. 

" When the ground already contains all the other con- 
stituents which the plant requires, as, for instance, a suffi- 
cient amount of the earthy phosphates, and of silicate of 
potass, the addition of the nitric salt will do good, by sup- 
plying nitrogen, and thus enabling the vegetable to assimi- 
late a proportionate quantity of the other ingredients. 

"But when the latter are already nearly exhausted, the 
addition of the nitrates will no longer be of advantage, 
since only that portion of nitrogen can be assimilated 
which is equivalent to the amount of the earthy phosphates, 
of the silicate of potass, and of the other fixed ingredients, 
which the plant obtains from the soil. 



PRACTICAL INFERENCES. 273 

"Hence, the proper remedy in such a case would seem 
to be, that of applying some other manure, which may fur- 
nish a due supply of the deficient matters. 

"Thus, if the nitrates have failed, we should be inclined 
to try the next year the effect of phosphate of lime, or of 
animal manure, upon the same soil. 

" But it seems to happen sometimes, that the same land, 
which is benefited by the administration of one kind of nitric 
salt, is scarcely affected by another. 

"This anomaly presented itself in an experiment on a 
small scale, which was tried at my request, by my broth- 
er, the Rev. E. Daubeny, on his farm, in the vicinity of 
Cirencester. 

"The subsoil is a stiff" retentive clay, resting upon the 
cornbrash limestone, and the farm, before it came into its 
present occupation, was in an exhausted condition, though 
it has latterly yielded somewhat better returns. 

"A coarse analysis of a sample, conducted according to 
the method recommended by Mr. Rham, in the Journal of 
the English Agricultural Society,* afforded me the follow- 
ing results : 

"1000 grains contained, 607, of impalpable powder, consisting of 

Water . . . . .57 

Humus ..... 57 

Silica . . . . .64 

Alumina mixed in the silica . . 24 

Oxide of iron . . . .19 

Carbonate of lime ... 90 

Magnesia .... a trace 

. Clay 296 

Total . . . . . " 607 

And 388 of coarser materials, separated by 
Sieve . . No. 1. the coarsest 117^ consisting 

Sieve . No. 2. . . 151 | chiefly of 

Sieve . . No. 3. the finest 120 I clay, with 

(50 grs. of 

Total . . . . . 388 carbonate 

Loss .... 5 J of lime. 

"Four equal strips of this land, each somewhat ex- 
ceeding i of an acre, and contiguous one to the other, 
which had been sown with wheat in the autumn of 1839, 
were measured out. 

"The first of these, which lay next to the hedge, was 
left without any addition of manure. 

"The second, adjoining, had a top-dressing of ^ cwt. of 
nitrate of potass given it in April. 

" * Number 1, page 46." 



274 APPENDIX TO PART I. 

"The third portion was left, like the first, without 
addition. 

"The fourth, or that farthest from the hedge, had a 
similar top-dressing of nitrate of soda applied at the same 
period. 

"The salts were respectively scattered over the strips 
of land in as uniform a manner as possible, and became 
diffused through the soil, by means of the showers which 
followed shortly after their application. 

" As the wheat advanced towards maturity, the nitrated 
patches were distinguishable, by the more vivid greenness 
of the crop, and by its standing up somewhat above the 
general level, but this difference was less perceptible at a 
later stage of its progress. 

" In the autumn the whole was reaped as usual, and the 
following results obtained : 

" No. 1. produced only 5 bushels, 54 lbs. of grain, or 23 
bushels, 36 lbs. to the acre, but the crop had been ac- 
cidentally trodden by sheep, and much devoured by birds. 
The straw was not weighed. 

"No. 2. produced 7 bushels, 57 lbs., or 31 bushels, 48 
lbs. to the acre, and 520 lbs. of straw = 1 ton, cwt. 80 lbs. 
to the acre. 

"No. 3. produced 6 bushels, 54 lbs., or 27 bushels, 36 
lbs. to the acre, and 421 lbs. of straw = 16 cwt. to the acre. 

"No. 4. produced 6 bushels, 48 lbs., or 27 bushels, 
12 lbs. to the acre, and 432 lbs. of straw = 15 cwt. 48 lbs. 
to the acre. 

" With respect to weight, that of No. 2. was 62^ lbs. to 
the bushel, that of No. 3. and 4. was only 62 lbs. 

"Now 3| lbs. of flour from No. 3, produced of bread 
4 lbs. 4 ozs. 

" Whereas 3| lbs. from No. 2. produced 4 lbs. 14 ozs. 

" Hence the difference, between the produce of the strip 
of ground which had been manured with nitrate of potass, 
and that which had received no manure, may be caJculated 
as follows : 

"Amount of produce, of 
Bu. lbs. 

"No. 3 6 54 = 6. 

"No. 2 7 57 = 7. 

" As 6 : 7 : : 100 : 120, or 20 percent, of increase in the 
amount of produce. 

"To which add, that the^quantity of flour, that in No. 



PRACTICAL INFERENCES. 275 

3 had produced 4 lbs. 4 ozs. of bread, in No. 2. produced 

4 lbs. 14 ozs. Now 

"As 4 lbs. 4 ozs. : 4 lbs. 14 ozs. : : 100 : 114. 

"Showing an increase per cent, of 14 -|- 20 = 34 per 
cent. 

"Now if we calculate the wheat as worth eight shillings 
a bushel, the profit of using the nitrate of potass will stand 
as follows : 

"27 bushels 36 lbs. at 8.<J. = 11/. value of the produce on 
the non-nitrated land : add 34 per cent, or |rd = 3/. 13», 
4d., for the value of the nitrated, which, after deducting 
1/. 10s. for the value of a cwt. of nitrate of potass, and for 
carriage, will leave to the farmer a clear profit of 2/. 3s. 4d. 

" The superior absorbing power of the nitrated flour, 
over the non-nitrated, was found to depend upon the pres- 
ence of a larger amount of gluten, for I discovered in the 
former 740 grs. in the pound, or 13 per cent. ; in the latter 
850 grs. in the pound, or 15 per cent, of that ingredient, 
the difference being 2 per cent, in favor of the nitrated 
wheat, a result which confirms, in a very satisfactory man- 
ner, the statement of Mr. Hyett.* 

"But how are we to account for the failure of the nitrate 
of soda, on soil which had been so materially benefited by 
the administration of nitrate of potass .'' 

"The small scale upon which the experiment was 
conducted, may render us reluctant to build much upon 
the results obtained, until it has been again repeated, but 
supposing the fact to be hereafter confirmed, I can only 
conjecture, that the difference must have arisen from a 
deficiency in the land, of potass, which would be supplied 
by the saltpetre, but not by the nitrate of soda, "f Should 
this be the true solution, those soils, in which nitrate of soda 
has succeeded, ought to contain a larger quantity of potass, 
than those in which it has failed. 

"The general principles laid down may also inform us, 
as to the true plan upon which the succession of our crops 
should be regulated. 

"Those plants ought to succeed each other, which con- 
tain different chemical ingredients, so that the quantities 

" * The amount of gluten is smaller than in the samples reported on 
by Mr. Hyett, but my gluten was dried, with the greatest care, under 
the exhausted receiver of an air-pump, with sulphuric acid, till it 
ceased to lose weight." 

" t Nitrate of soda is stated to exist in barley, but it has not been de- 
tected in wheat. It would therefore be worth while to see, whether 
the above salt is particularly suited to the former crop." 



276 APPENDIX TO PART I. 

of each, which the soil at any given time contains, may be 
absorbed in an equal ratio. 

"Thus a productive crop of corn could not be obtained, 
without the phosphates of lime and magnesia which are 
present in the grain, nor without the silicate of potass which 
gives stability to the stalks. 

"It would be injudicious, therefore, to sow any plant 
that required much of any of the above ingredients, imme- 
diately after having diminished the amount of them present 
in the soil, by a crop of wheat, or of any other kind of corn. 

" But, on the other hand, leguminous plants, such as 
beans,Vire well calculated to succeed to crops of corn, be- 
cause they contain no free alkalies, and less than one per 
cent, of the phosphates. 

"They thrive, therefore, even where these ingredients 
have been withdrawn, and during their growth, atford time 
for the ground to obtain a fresh supply of them, by a fur- 
ther disintegration of the subjacent rock. 

" For the same reason, wheat and tobacco may some- 
times be reared in succession in a soil rich in potass, be- 
cause the latter plant requires none of those phosphoric 
salts which are present in wheat. 

" In order, ho.wever, to proceed upon certain data, it would 
be requisite, that an analysis of the plants most useful to 
man should be accomplished in the different stages of their 
growth, a labor which has hitherto been only partially un- 
dertaken, and which perhaps is an object worthy to engage 
the attention of a great Body, like that of the English Ag- 
ricultural Association. 

" It is a curious fact, that the same plant differs in con- 
stitution when grown in different climates. Thus in the 
beet-root, nitre takes the place of sugar, when this plant is 
cultivated in the warmer parts of France.* 

"The explanation of this difference is probably as fol- 
lows : — 

"Beet-root contains, as an essential ingredient, not only 
saccharine matter, but also nitrogen, and it is probable, 
that the two are mutually so connected together in the veg- 
etable tissue, that the one cannot exist without the other. 
The nitrogen, being derived from the decomposition of am- 
monia, must be affected by any cause which diminishes the 
supply of the latter ; and in proportion as this ingredient 
is wanting, the secretion of sugar will likewise fall off. 
" Now, it has been shown by Liebig, that the formation 

"* See Chaptal." 



PRACTICAL INFERENCES. 277 

of nitric acid is owing to the decomposition of ammonia, 
and it is conceived by him, that the last products of the de- 
composition of animal bodies present themselves, in the 
form of ammonia in cold, and in that of nitric acid in warm 
climates. * Hence, in proportion to the amount of nitric 
acid formed, and of nitre absorbed by the plant, that of the 
nitrogen, and consequently that of the saccharine matter, 
present in it, may be diminished. 

"We may also be guided in the management and selec- 
tion of manures, by the principles above laid down. The 
solid excrement of animals varies of course in composition 
according to the nature of their food : thus that of herbivo- 
rous animals, which are fed principally on grasses, contains 
much silicate of potass, as well as phosphoric salts, but 
comparatively little nitrogen ; whilst human faeces contain 
little of the former ingredient, but much phosphate, and a 
larger proportion of nitrogen. There will be seen even a 
difference in these respects between the manure afforded by 
the inhabitants of towns, fed principally upon animal food, 
and that of peasants, who subsist in a greater degree upon 
vegetables. 

"In like manner, the excrement of cattle is more effica- 
cious as manure, when the animal is well fed, and under- 
going the fatting process, than when it is more scantily 
nourished. 

" According to Sprengel, there is a difTerence between 
different kinds of herbivorous animals in this respect, cows 

* " I have seen no attempt to account for the formation of nitrate of 
soda in such large quantities in Peru, and may therefore offer the fol- 
lowing, as at least a plausible solution. 

'• Wherever salt lakes occur, which become partially or wholly dried 
up during a part of the year, carbonate of soda will be formed from the 
decomposition of common salt. This I have observed myself on the 
sandy plains of Hungary, in the neighborhood of Pesth. Now if any 
circumstances should concur in such spots, calculated to generate nitric 
acid, the latter, by its stronger affinity for the alkali, would take the 
place of tiie carbonic acid, and nitrate of soda would result. 

"Tliis, however, being a deliquescent salt, would not accumulate on 
the surface, except in countries like Peru, remarkable for their extreme 
dryness. 

" But how are we to account for the generation of so large a quanti- 
ty of nitric acid in this locality.'' 

" If we suppose with Mr. Darwin, that the district in which the salt 
is found was once a lake or inland sea, its change to dry land must have 
caused the destruction of all its marine inhabitants. Now the decom- 
position of their exuvite would, in a warm climate, present themselves, 
as stated in the text, in the form, rather of nitric acid, than of ammonia. 

" Hence the production of so much nitrate of soda in Peru, is attrib- 
utable to the heat ; its preservation to the dryness of the climate." 

24 



278 APPENDIX TO PART I. 

requiring, for the chemical constitution of their body, or 
for the formation of their milk, more nitrogen, and more 
phosphate of lime, than sheep ; whilst the latter require 
again more sulphur, and moie common salt, for the forma- 
tion of their wool. Hence the excrements of oxen contain 
less nitrogen than those of sheep, whilst they are more 
abundant in salt and sulphur. 

" Accordingly it is found in practice, that sheep's dung 
ferments more readily than that of black cattle. 'The 
latter, therefore,' says Liebig, ' is of most service on soils 
consisting of lime and sand, which contain no silicate of 
potass or phosphates, whilst their value is much less when 
applied to soils formed of argillaceous earth, basalt, gran- 
ite, porphyry, clinkstone, and even mountain limestone, 
because all these contain potass in considerable quantity.' 

"Human excrements, on the contrary, are useful in 
both descriptions of soil, but would be inadequate to supply 
the silicate of potass which is wanting in the former. 

"The constituents, however, to which the solid excre- 
ments of animals in general owe their principal efficacy 
are the earthy phosphates ; and hence we see, why it is 
that animal manure should favor the growth of corn, which 
contains so much phosphate of lime and magnesia, and 
why the earth of bones, and even the ashes of certain 
kinds of wood, such as the beech, which contain phos- 
phates, may be advantageously substituted, whilst the ash- 
es of others, as of the oak and fir, which are deficient in 
the phosphates, are of very little avail. 

" We see also the cause of the fertilizing quality of 
liquid manure, as employed in Holland, for those crops 
which are most subservient to the nourishment of man. 

"Liquid manure consists in a great degree of the urine 
of various animals, which, during its decomposition, exhales 
a larger quantity of ammonia than any other species of 
excrement. 

" Now all kinds of corn contain nitrogen, and conse- 
quently any manure which yields a ready supply of ammo- 
nia, must cause a fuller development of those parts of the 
plant which are of the greatest use to man. 

"Even the kind of animal manure usually employed in 
this country owes its efficacy, so far as it is dependent 
upon the ammonia present, to the urine, rather than to the 
solid excrement, of which it is made up, and hence be- 
comes materially deteriorated in this respect, when the 
more liquid portions are allowed to drain off from it. 



PRACTICAL INFERENCES. 279 

"We may also derive from these considerations, some 
useful cautions, as to the treatment of this same material. 

"Ammonia, in the free or uncombined condition in which 
it is generated from the decomposition of animal substances, 
is caustic and noxious to vegetation, and is likewise so 
volatile that it will escape into the atmosphere so soon as 
it is produced, unless some means are taken to detain it. 

" 'J'his causticity is readily removed by promoting its 
combination with the carbonic acid of the atmosphere, but 
to prevent its escape during the time necessary for effect- 
ing this union, various expedients have been resorted to. 

"Where water in sufficient quantity is present, along 
with the other materials of the dung-heap, this alone will 
in some measure tend to prevent its volatilization, and the 
same object is further secured, by admixture with peat, a& 
recommended by Lord Meadowbank, or with sawdust, 
tanner.'s bark, turf, and other similar substances. These 
too are beneficial, not only by moderating the putrefactive 
process, but also by detaining the ammonia generated 
within their pores, and thus preventing its loss. 

"The advantage of compost heaps, which are strongly 
advocated by some farmers, depends mainly on these prin- 
ciples. 

"The method recommended by a writer, in a late num- 
ber of the English Agricultural Journal,* to whom a prize 
of ten sovereigns was awarded for his Essay, consisted, in - 
first making a substratum of peat |ths, and sawdust |th ; 
spreading over it the dung from the cattle-sheds, and the 
urine preserved for the purpose in tanks contiguous ; and 
then, after allowing the mixture to remain exposed for a 
week, covering it with a fresh layer, nine inches or a foot 
thick, of peat and sawdust, or of peat alone. 

"Several such alternations of peat and manure are to 
be piled one above the other during the winter, great care 
being always taken, that the peat should be as dry as pos- 
sible, by exposing it previously for several months to the 
weather. 

"Now it will be immediately perceived, that these 
recommendations of a practical farmer completely fulfil 
the conditions, which theory suggests, for making the best 
use of our manure, by first neutralizing the ammonia, and 
afterwards detaining it within the pores of a spongy sub- 
stance, until it is spread over the land. 

"The most effectual plan, however, of preventing its 

"* Part II p. 13D." 



280 APPENDIX TO PART I. 

loss, would seem to be, not to wait for the slower action 
of carbonic acid upon it, but to combine it directly with 
those acids, which form with it salts fixed at common tem- 
peratures. 

"Hence, Liebig advises the addition of sulphuric or of 
muriatic acid, both cheap substances, to the other materials 
of the dung-heap, which, forming with the ammonia pres- 
ent, the sulphates and muriates of that alkali, would at 
once prevent any loss of it by evaporation. 

" If these expedients be not adopted, it should at least be 
borne Jr mind, that unless means are taken to prevent it, 
the most valuable portion of the manure is constantly 
escaping, during exposure to air and sun, by evaporation, 
and also by draining off into the ground, whence, instead 
of a material calculated to afford a ready supply of nitro- 
gen to the plant, we obtain an effete mass, in which that 
element is in a great measure wanting, and which, there- 
fore, can only influence the growth of plants, by virtue of 
the phosphoric salts and other fixed ingredients still pres- 
ent in it. 

"These views also throw some new light upon the use 
of gypsum, or sulphate of lime, as a manure to certain 
crops. 

. " The fact, that leguminous plants contain this substance 
as an essential ingredient, may in some measure explain 
its fertilizing effect on them, but it is also found serviceable 
to turnips and cabbages, which do not appear to contain it, 
nor does it seem easy thus to explain the superior advan- 
tage said to arise, from scattering it in fine powder over 
the leaves of clover and saintfoin, as is practised in France 
and in North America, and with such manifest good effect, 
that, it is said, if the substance be partially applied to a 
field, the portions that have received this dressing may 
afterwards be distinguished from the rest by the superior 
luxuriance of the crop. 

"Liebig, therefore, has suggested another mode in 
which gypsum may be beneficial to crops in general, by 
reference to the property which it possesses, of depriving 
ammonia of its volatility, and thus preventing its escape 
into the atmosphere. 

"This effect arises from the double decomposition which 
lakes place, when sulphate of lime and carbonate of ammo- 
nia are brought together, the lime being converted into a 
carbonate, and the ammonia uniting with sulphuric acid. 

"The above theory of its use being admitted, we may 



PRACTICAL INFERENCES. 281 

be encouraged to extend its application to other crops 
besides the Leguminosae, and also to mix it with the dung 
of our stables, so as to prevent the waste of this valuable 
material, which is constantly occurring. (See p. 191.) 

" But the farmer must be reminded, that it will be neces- 
sary, that the sulphate of ammonia resulting from the 
action of the gypsum, should be brought into contact with 
some substance capable of slowly decomposing it, so as to 
supply ammonia to the plant. 

"For there is no reason to believe, that the organs of a 
vegetable can decompose sulphate of ammonia, and if they 
were able so to do, the disengagement of free sulphuric 
acid in consequence could hardly fail to be injurious to 
their structure. 

"Now a soil consisting of pure sand, or of clay, would 
be incapable of acting upon this salt, but contradictory as 
it may seem to the fact, that carbonate of ammonia is 
decomposed by sulphate of lime, carbonate of lime does 
appear in a slight degree to disengage ammonia even in 
the cold, as may be seen by the change of color produced 
in a piece of turmeric or reddened litmus paper, placed 
over a vessel containing powdered chalk, as soon as it is 
moistened with a solution of sulphate of ammonia. 

"And since this interchange of constituents is effected 
rapidly under the influence of a high temperature, as hap- 
pens in the common method of obtaining carbonate of 
ammonia artificially by double decomposition, it is worth 
inquiry, whether it may not be favored likewise by exposure 
to solar heat and light. 

" Where calcareous matter, therefore, exists in the soil, 
ammonia may be slowly supplied in this manner to the 
growing plant, and it is possible even, that the carbonate 
of lime, which seems to be generally present in the sap, 
may act in the same manner. 

"In this way we may readily explain the use of scatter- 
ing gypsum over the leaves of clover shortly before a 
shower of rain. The ammonia present in the latter is thus 
detained, and converted into sulphate by the action of the 
gypsum upon it, and when introduced into the system by 
the absorbing surfaces of the plant, it may be again con- 
verted into carbonate, by the slow action of the carbonate 
of lime present in the sap. 

"When, however, a more rapid disengagement of am- 
moniacal gas is required for the nutrition of the intended 
crop, we ought not to trust to the slow action of carbonate 

24* 



282 APPENDIX TO PART I. 

of lime, but should ap|)ly quicklime to the spots over which 
the manure has been scattered. 

"It is probably in part by setting at liberty the volatile 
alkali imprisoned in the soil, that quicklime acts so bene- 
ficially in agriculture, and in particular, that it improves 
soil containing a free acid, such as peat earth ; for, inde- 
pendently of its use in neutralizing a substance, which 
checks vegetation by its antiseptic properties, quicklime 
may also disengage a portion of ammonia combined with 
this acid, and thus atford to the plant a more abundant 
supply oi! the nitrogen, which it requires. 

"Chloride of calcium, common salt, sulphuric and mu- 
riatic acids, phosphate of lime, and other salts, may, it 
would seem, on the principles laid down, be substituted, 
when gvpsum cannot be obtained. 

"The chlorides, indeed, like certain oxides, (such as 
water and carbonic acid,) seem to be decomposed by the 
plant under the influence of light, for chlorine is exhaled 
by vegetables near the sea, as oxygen is in other situations. 
Hence, if muriate of ammonia should result from the 
action of common salt upon the carbonate of ammonia 
present in rain, it may undergo decomposition when ab- 
sorbed by the plant, and contribute in consequence to sup- 
ply it with nitrogen. 

"The above considerations may suggest to us the utility 
in agriculture of ammoniacal compounds of all kinds, as 
substitutes for animal manure. 

" Sal ammoniac is probably too expensive an article to 
be employed ; but sulphate of ammonia may be had of the 
wholesale chemist at a price considerably more reasonable, 
namely, at 22/. per ton ; and the ammoniacal liquor, which 
is afforded in abundance by our gas manufactories, through 
the distillation of coal, is a still cheaper commodity. 

"The latter consists principally of carbonate of ammo- 
nia, mixed with a certain proportion of the hydro-sulphuret, 
and, until its use in agriculture was discovered, much of it 
was allowed to run waste into the Thames, where its nox- 
ious qualities destroyed the fish, and rendered the water 
unpalatable and disgusting;. 

" Its efficacy as a manure is vouched for by many who 
have made trial of it upon their land,* and although the 
hydro-sulphuret of ammonia in a concentrated form would 
doubtless be fatal to vegetation, yet in a proper state of 

" * See a communication by Mr. Paynter, on Gas- water as a Manure, 
Eng. Agricult. Journ. No. 1, p. 4." 



PRACTICAL INFERENCES. 283 

dilution it may be of service to certain crops, not merely 
by virtue of the ammonia, but also in consequence of the 
sulphuretted hydrogen, which it contains, since the latter 
is found to be an ingredient in the turnip, and in some 
other tribes of cruciferous plants. 

"Where, however, it is found troublesome to preserve, 
or difficult to convey to a distance this volatile material, an 
easy method presents itself for retaining for any length of 
time the ammonia present in it. 

"This is done, by availing ourselves of the same prin- 
ciple which has been already explained to you, in treating 
of the uses of gypsum as a manure ; for as the gas liquor 
consists of ammonia, combined principally with carbonic 
acid, it is evident, that it may be converted into a sulphate 
by admixture with sulphate of lime. 

"I am indebted to an excellent scientific chemist* for 
the following details, which may be of use to the agricul- 
turist in enabling him to appreciate the importance of this 
commodity, and to prepare for himself any quantity that he 
may require for his farm. 

"One gallon of the ammoniacal liquor added to 1 lb. 2-^ 
ozs. of powdered but not calcined gypsum, will produce 
I lb, of crystallized sulphate of ammonia. To effect the 
decomposition, the materials should be mixed and stirred 
up together for ten or twelve hours, a heat, below that of 
ebullition, being at the same time employed. The suljjhate 
of ammonia remains in solution, and may be obtained in a 
solid state, by evaporating at a low temperature. 

"Theory would suggest, that this material ought to sup- 
ply nitrogen to the crop at a much cheaper rate than the 
nitrates employed for that purpose. For let us suppose, 
that the farmer wishes to add to his land 60 lbs. of crys- 
tallized sulphate of ammonia. This may be obtained by 
introducing about 70 lbs. of powdered gypsum uncalcined 
into 50 gallons of ammoniacal liquor ; for my informant 
found, that one gallon mixed with chloride of calcium 
yielded 4800 grs. of carbonate of lime, equivalent to about 
7200 grs. of crystallized sulphate of ammonia, or 1 lb. 3 
ozs. Now 4800 grs. of carbonate of lime are equivalent 
to 8250 grs., or to 1 lb. 5 ozs. of sulphate of lime, with 2 
atoms of water. 

"This, therefore, is the quantity of gypsum required, to 



'• * Mr. Richard Phillips, the superintendent of the chemical depart- 
ment of the establishment, connected with the Museum of Economic 
Geology, lately instituted by government." 



284 APPENDIX TO PART I. 

convert the contents of 1 gallon of gas liquor into sulphate 
of ammonia, and accordingly, 50 gallons will require 70 
lbs. of gypsum, and will produce about 60 lbs. of the am- 
moniacal sulphate. 

"Now since the price per ton of gypsum is from 2/. to 
3/., the cost of 70 lbs. of it cannot exceed 2s., and the 
labor of mixing the materials may be reckoned at about as 
much more ; so that to a gas company, where this liquor, 
not being employed for manufacturing any of the salts of 
ammonia, has hitherto been regarded as so much refuse, 
and where the heat requisite for evaporating and crystal- 
lizing the product can be obtained with scarcely any in- 
creased expenditure, the cost of the impure sulphate would 
not exceed one penny per pound. 

' ' This then is less than half the cost of an equal quantity 
of nitrate of soda, which at its present price (23s. per 
cwt.) may be reckoned at two-pence-halfpenny a pound, 
and yet it may be shown, that a given weight of sulphate 
of ammonia contains more ammonia, and consequently 
ought to yield more nitrogen, than nitrate of soda.* 

" Sulphate of ammonia 75 pis. contain of ammonia 17= nitrogen iJ. 

whilst 
Nitrate of soda .... 86 pts 17= 14. 

" So far as theory goes, therefore, the balance would 
seem to be in favor of the efficiency of sulphate of am- 
monia over nitrate of soda, in the proportion of 75 to 86. 

"These considerations are merely offered, by way of 
encouragement to those who may be disposed to make trial 
of this promising kind of manure, and of course v.'ill go 
for little until they have been tested by experiment. 

"There are other materials also employed as manure, 
which appear to owe their efficacy to the presence of am- 
monia, — such, for example, as soot, which contains a con- 
siderable proportion of this principle united with carbonic 
acid, and which accordingly has for a long time been ad- 
vantageously employed as a top-dressing to land. 

"Lastly, the foregoing considerations point out the de- 
cided superiority of human to other sorts of animal manure. 

" Independently of its being richer in most of those in- 
gredients on which the fertilizing property of manure de- 
pends, the following circumstance gives it an advantage. 

"* Nitrate of potass ought to contain ten per cent, less nitric acid 
than nitrate of soda, hut, as it is a less deliquescent salt, the difference 
uetween the two, as obtained in commerce, is not very considerable." 



PRACTICAL INFERENCES. 285 

" When the excrements of the horse or ox are employed, 
we are obliged to allow of their undergoing a long previous 
process of fermentation, by which a large proportion of their 
valuable matter is got rid of, in order, as much as possible, 
to destroy the vitality of the seeds, which pass undigested 
along with the faeces. And after all many still remain, 
and are thus introduced into the fields when the manure is 
scattered over them. 

"By the use of night-soil we avoid this inconvenience, 
and hence it is, that in China, where it is exclusively em- 
ployed, the corn-fields are remarkably exempt from weeds. 

" Chemistry has suggested means for destroying those 
offensive qualities which have hitherto limited the use of 
this species of manure, although it is stated by Liebig, 
that the method adopted for that purpose on the Continent 
is defective, inasmuch as a large proportion of their am- 
moniacal contents is allowed to escape. 

" Even under its present management, however, the pro- 
cess may be regarded as one of the most important pres- 
ents which chemistry has yet made to the practical farmer, 
by rendering the accumulated filth of a large capital avail- 
able for his purposes, in the remotest corner of the British 
empire." 

Professor Daubeny concludes his lecture with some high- 
ly ingenious speculations on the primary source of the 
carbon and nitrogen present in plants and animals. He 
does not deem it probable that a quantity of organic 
matter was called into existence at once, sufficient to sup- 
ply the v/hole of the succeeding races of plants and ani- 
mals with these ingredients ; or that the whole, which is 
now condensed in the organization of the animal and vege- 
table kingdoms, was at any one time present in the atmo- 
sphere ; but that the carbon and nitrogen of plants was 
originally supplied from the interior of the earth by vol- 
canos. The fertility of the neighborhood of Naples Dr. 
D. attributes to volcanic exhalations. 

"Once grant," he continues, "with Liebig, that the 
nitrogen, which plants possess, can only be obtained by 
them through the decomposition of ammonia, and it will 
follow, that unless this gas be supplied from the interior of 
the globe, the quantity of organic matter, into which this 
principle enters as a component part, will be undergoing 
a continual diminution. 

"For we know of no natural processes taking place on 
the surface of the globe, which generate ammonia, ex- 



286 APPENDIX TO PART I. 

cepting those connected with animal and vegetable decompo- 
sition ; whilst there are many, such as the combustion of 
various organic substances, which, by resolving bodies 
containing nitrogen into their constituent elements, would 
have diminished the aggregate amount of them which might 
have formerly existed. 

" Some compensating process, therefore, is clearly re- 
quired, and that, if I mistake not, is the disengagement of 
ammoniacal gas from the interior of the globe." 

" Granting, then, what upon Liebig's principles seems 
most consistent with analogy, namely, that the ammonia, 
no less^han the carbonic acid, which formed the food of 
the first plants, has been produced, not by processes of ani- 
mal decay, but by such as were proceeding within the globe 
prior to the creation of living beings, the notion of a slow 
and continuous disengagement of both compounds, from the 
earliest period to the present time, will be received perhaps, 
as at loast the most probable mode of accounting for their 
unfailing supply. 

" Whilst it relieves us from the difficulty of supposing the 
atmosphere surcharged with these gases at any one period, 
it suggests to us, at the same time, sublime and interesting 
views of the arrangements of the Deity, in thus having made 
all things subservient to one common end, and having or- 
dained, that the mighty agents of destruction, which exist 
in the bowels of the earth, should minister, like the malig- 
nant Genii of some eastern fable, to the wants and necessities 
of the living beings, which He has placed upon its surface." 



USE OF PHOSPHATE OF SODA IN CALICO PRINTIKG.* 

(See page 186.) 

The discovery of the principle which led to the use of 
phosphate of soda, was made in the United States, by Dr. 
Dana, of Lowell. The first practical application of the 
salt was made, in consequence of Dr. Dana's researches, 
by Mr. J. D. Prince, Jr., at the works of the Merrimack 
Manufacturing Company in Lowell, in 1834. Mr. J. D. 
Prince, Sen., the scientific and accomplished superintend- 
ent of the establishment, was engaged with Dr. Dana for a 

* Substance of a communication from Dr. Dana. 



DANIELL'S ARTIFICIAL MANURE. 287 

series of years on this subject. - In 1839, Mr. Prince, Jr. 
carried the process to England, and, with Mr. J. Mercer and 
Blyth, took out letters patent. Mr. Prince sold his right to 
Messrs. Mercer and Blyth, who introduced the process into 
the establishments on the Continent. The article is now 
made by M. Kestner, of Thann, who observes, in his letter 
to the "Societe Industrielle de Mulhouse," accompanying 
a sample, and on which their committee reported, Bulletin 
No. 6 3, that "the article is the invention of Messrs. Mercer 
and Blyth, printers of calicoes near Manchester." 

Dr. Liebig probably derived his knowledge of this im- 
provement from the Bulletin referred to above, and his 
statement is only partial respecting the effects of cow-dung. 
The discovery of the principle of its action has led to the 
employment of other salts, which produce effects equally 
good as phosphates. 



DANIELL S ARTIFICIAL MANURE.* 

The basis of this manure is wood reduced to powder, 
sawdust, which is to be thoroughly saturated with bituminous 
and animal matters of all or any kind ; to this is to be 
added small proportions of soda and quicklime. The 
sample exhibited to the Royal Agricultural Society, was a 
coarse black powder, having a strong smell, somewhat 
resembling coal tar. In England its price will be about 
one third that of bone dust. It is a kind of artificial 
bituminous coal. It should be buried two or three 
inches under the surface of the soil. For grass land, 
it is to be well mixed with a considerable portion of 
ordinary unvalued mould. The quantity to be used will 
vary with the crop. About twenty-four bushels per acre 
are recommended for wheat, and half as much more, 
or thirty-si.K bushels, may be carefully applied for turnips 
or mangel-wurtzel. Its direct effect is thought to be the 
conveyance to the soil of the direct nutriment of future 
growth. This effect is produced by the supply of ammo- 
nia to the soil in substances calculated to retain it for a 
time, — to again absorb it from the atmosphere, — as they 
give it out to plants during their growth. It will probably 
prevent also the ravages of insects. 

* Abridged from notices in the New Genesee Farmer, Vol. III., by 
J. E. T. . > J' 



PART II. 

OF THE CHEMICAL PROCESSES OF FERMENTATION, 
DECAY, AND PUTREFACTION. 



CHAPTER I. 

CHEMICAL TRANSFORMATIONS. 

Woody fibre, sugar, gum, and all such organic 
compounds, suffer certain changes when in contact 
with other bodies ; that is, they suffer decomposition. 

There are two distinct modes in which these de- 
compositions take place in organic chemistry. 

When a substance composed of two compound 
bodies, crystallized oxalic acid for example, is brought 
in contact w4th concentrated sulphuric acid, a com- 
plete decomposition is effected upon the application 
of a gentle heat. Now crystallized oxalic acid is a 
combination of water with the anhydrous acid ; but 
concentrated sulphuric acid possesses a much greater 
affinity for water than oxalic acid, so that it attracts 
all the water of crystallization from that substance. 
In consequence of this abstraction of the water, an- 
hydrous oxalic acid is set free; but as this acid can- 
not exist in a free state, a division of its constitu- 
ents necessarily ensues, by which carbonic acid and 
carbonic oxide are produced, and evolved in the 
gaseous form in equal volumes. In this example, 
the decomposition is the consequence of the removal 
of two constituents (the elements of water), which 
unite with the sulphuric acid, and its cause is the 
superior affinity of the acting body (the sulphuric 
acid) for water. In consequence of the removal of 
25 



290 CHEMICAL TRANSFORMATIONS. 

the component parts of water, the remaining ele- 
ments enter into a new form ; in place of oxalic acid, 
we have its elements in the form of carbonic acid 
and carbonic oxide. 

This form of decomposition, in which the change 
is effected by the agency of a body which unites with 
one or more of the constituents of a compound, is 
quite analogous to the decomposition of inorganic 
substances. When we bring sulphuric acid and ni- 
trate^pf potash together, nitric acid is separated in 
consequence of the affinity of sulphuric acid for pot- 
ash ; in consequence, therefore, of the formation of 
a new compound (sulphate of potash). 

In the second form of these decompositions, the 
chemical affinity of the acting body causes the com- 
ponent parts of the body which is decomposed to 
combine so as to form new compounds, of which 
either both, or only one, combine with the acting 
body. Let us take dry wood, for example, and moist- 
en it with sulphuric acid ; after a short time the wood 
is carbonized, while the sulphuric acid remains un- 
changed, with the exception of its being united with 
more water than it possessed before. Now this wa- 
ter did not exist as such in the wood, although its 
elements, oxygen and hydrogen, were present ; but 
by the chemical attraction of sulphuric acid for wa- 
ter, they were in a certain measure compelled to 
unite in this form ; and in consequence of this, the 
carbon of wood was separated as charcoal. 

Hydrocyanic acid* and water, in contact with hy- 
drochloric acid,t are mutually decomposed. The 
nitrogen of the hydrocyanic acid, and a certain quan- 
tity of the hydrogen of the water, unite together and 
form ammonia; whilst the carbon and hydrogen of 
the hydrocyanic acid combine with the oxygen of the 
water, and form forinic acid. % The ammonia com- 

* See pag;e 70. note. 

i Formerly called Muriatic Acid, obtained from sea salt and compos- 
ed of Hydrogen and Chlorine in equal vols. H -|- CI. 
I See page 70. 



EXAMPLES. 291 

bines with the muriatic acid. Here the contact of 
muriatic acid with water and hydrocyanic acid caus- 
es a disturbance in the attraction of the elements of 
both compounds, in consequence of which they ar- 
range themselves into new combinations, one of 
which, — ammonia, — possesses the power of uniting 
with the acting body. 

Inorganic chemistry can present instances analo- 
gous to this class of decomposition also ; but there 
are forms of organic chemical decomposition of a 
very different kind, in which none of the component 
parts of the matter which suffers decomposition enter 
into combination with the body which determines the 
decomposition. In cases of this kind a disturbance 
is produced in the mutual attraction of the elements 
of a compound, and they in consequence arrange 
themselves into one or several new combinations, 
which are incapable of suffering further change under 
the same conditions. 

When, by means of the chemical affinity of a sec- 
ond body, by the influence of heat, or through any 
other causes, the composition of an organic compound 
is made to undergo such a change, that its elements 
form two or more new compounds, this manner of 
decomposition is called a chemical transformation or 
metamorphosis. It is an essential character of chem- 
ical transformations, that none of the elements of the 
body decomposed are singly set at liberty. 

The changes, which are designated by the terms 
fermentation, decay, and putrefaction, are chemical 
transformations effected by an agency which has 
hitherto escaped attention, but the existence of 
which will be proved in the following pages. 



292 CHEMICAL TRANSFORMATIONS. 



CHAPTER II. 

ON THE CAUSES WHICH EFFECT FERMENTATION, DECAY,* 
AND PUTREFACTION. 

Attention has been recently directed to the fact, 
that a body in the act of combination or decomposi- 
tion t*xercises an influence upon any other body with 
which it may be in contact. Platinum, for example, 
does not decompose nitric acid ; it may be boiled 
with this acid without being oxidized by it, even 
when in a state of such fine division, that it no long- 
er reflects light (black spongy platinum). But an 
alloy of silver and platinum dissolves with great ease 
in nitric acid; the oxidation which the silver suffers, 
causes the platinum to submit to the same change ; 
or, in other words, the latter body, from its contact 
with the oxidizing silver, acquires the property of 
decomposing nitric acid. 

Copper does not decompose water, even when 
boiled in dilute sulphuric acid; but an alloy of cop- 
per, zinc, and nickel, dissolves easily in this acid 
with evolution of hydrogen gas. 

Tin decomposes nitric acid with great facility, but 
water with difficulty ; and yet, when tin is dissolved 
in nitric acid, hydrogen is evolved at the same time, 
from a decomposition of the water contained in the 
acid, and ammonia is formed in addition to oxide 
of tin. 

In the examples here given, the only combination 
or decomposition which can be explained by chemi- 
cal affinity is the last. In the other cases, electrical 

* An essential distinction is drawn in the following part of the work, 
between decay and putrefaction {Vcrwesung und Fdulniss), and they are 
shown to depend on different causes ; but as tlie word decay is not gen- 
erally applied to a distinct species of decomposition, and does not indi- 
cate its true nature, I shall in future, at the sugo^eslinn of the author, 
employ the term cremacausis, the meaning of wliich has been already 
explained. — Eu. 



THEIR CAUSES. 293 

action ought to have retarded or prevented the oxi- 
dation of the platinum or copper while they were in 
contact with silver or zinc, but, as experience shows, 
the influence of the opposite electrical conditions is 
more than counterbalanced by chemical actions. 

The same phenomena are seen in a less dubious 
form in compounds, the elements of which are held 
together only by a feeble affinity. It is well known, 
that there are chemical compounds of so unstable a 
nature, that changes in temperature and electrical 
condition, or even simple mechanical friction, or con- 
tact with bodies of apparently totally indifferent na- 
tures, cause such a disturbance in the attraction of 
their constituents, that the latter enter into new 
forms, without any of them combining with the act- 
ing body. These compounds appear to stand but 
just within the limits of chemical combination, and 
agents exercise a powerful influence on them, which 
are completely devoid ot action on compounds of a 
stronger affinity. Thus, by a slight increase of tem- 
perature, th'^ elements of hypochlorous acid* sep- 
arate from one another with evolution of heat and 
light ; chloride of nitrogen explodes by contact w^ith 
many bodies, which combine neither with chlorine 
nor nitrogen at common temperatures ; and the con- 
tact of any solid substance is sufficient to cause the 
explosion of iodide of nitrogen, or fulminating silver. 

It has never been supposed that the causes of the 
decomposition of these bodies should be ascribed to 
a peculiar power, different from that which regulates 
chemical affinity, — a power which mere contact with 
the down of a feather is sufficient to set in activity, 
and which, once in action, gives rise to the decora- 
position. These substances have always been viewed 
as chemical compounds of a very unstable nature, in 
which the component parts are in a state of such 
tension, that the least disturbance overcomes their 
chemical affinity.' They exist only by the vis inc7'ti(v., 

* Formerly, protoxide of chlorine. 

25* 



294 CHEMICAL TRANSFORMATIONS. 

and any shock or movement is sufficient to destroy 
the attraction of their component parts, and conse- 
quently their existence in their definite form. 

Peroxide of hydrogen* belongs to this class of 
bodies ; it is decomposed by all substances capable 
of attracting oxygen from it, and even by contact 
with many bodies, such as platinum or silver, which 
do not enter into combination with any of its con- 
stituents. In this respect, its decomposition depends 
evidei>tly upon the same causes which effect that of 
iodide of nitrogen, or fulminating silver. Yet it is 
singular, that the cause of the sudden separation of 
the component parts of peroxide of hydrogen has 
been viewed as different from those of common de- 
composition, and has been ascribed to a new power 
termed the catalytic force. Now, it has not been con- 
sidered, that the presence of the platinum and silver 
serves here only to accelerate the decomposition; 
for without the contact of these metals, the peroxide 
of hydrogen decomposes spontaneously, although 
very slowly. The sudden separation of the constit- 
uents of peroxide of hydrogen differs from the de- 
composition of gaseous hypochlorous acid, or solid 
iodide of nitrogen, only in so far as the decomposi- 
tion takes place in a liquid. 

A remarkable action of peroxide of hydrogen has 
attracted much attention, because it differs from 
ordinary chemical phenomena. This is the reduction 
which certain oxides suffer by contact with this sub- 
stance, on the instant at which the oxygen separates 
from the water. The oxides thus easily reduced, 
are those of which the whole, or part at least, of 
their oxygen is retained merely by a feeble affinity, 
such as the oxides of silver and of gold, and perox- 
ide of lead. 

Now, other oxides, which are very stable in com- 
position, effect the decomposition of peroxide of hy- 

* A remarkable compound, consisting of 1 Hydrogen, and 2 Oxygen. 
See description and process for obtaining, in Webster's Cheinistry, 
p. 134. 



THEIR CAUSE. 295 

drogen, without experiencing the smallest change ; 
but when oxide of silver is employed to effect 
the decomposition, all the oxygen of the silver is 
carried away with that evolved from the peroxide 
of hydrogen, and, as a result of the decomposition, 
water and metallic silver remain. When peroxide 
of lead * is used for the same purpose, half its oxy- 
gen escapes as a gas. Peroxide of manganese may 
in the same manner be reduced to the protoxide, and 
ogygen set at liberty, if an acid is at the same time 
present, which will exercise an affinity for the pro- 
toxide and convert it into a soluble salt. If, for ex- 
ample, we add to peroxide of hydrogen sulphuric 
acid, and then peroxide of manganese in the state of 
fine powder, much more oxygen is evolved than the 
compound of oxygen and hydrogen could yield ; and 
if we examine the solution which remains, we find a 
salt of the protoxide of manganese, so that half of 
the oxygen has been evolved from the peroxide of 
that metal. 

A similar phenomenon occurs, when carbonate of 
silver is treated with several organic acids. Pyruvic 
acid, for example, combines readily with pure oxide 
of silver, and forms a salt of sparing solubility in 
water. But when this acid is brought in contact 
with carbonate of silver, the oxygen of part of the 
oxide escapes with the carbonic acid, and metal- 
lic silver remains in the state of a black powder. 
(Berzelius.) 

Now no other explanation of these phenomena 
can be given, than that a body in the act of com- 
bination or decomposition enables another body, with 
which it is in contact, to enter into the same state. 
It is evident that the active state of the atoms of one 
body has an influence upon- the atoms of a body in 
contact with it; and if these atoms are capable of 
the same change as the former, they likewise under- 

* A peroxide is one that contains the largest proportion of oxygen. 
When several compounds of metals and oxygen occur, that which con- 
tains the s;nallest proportion of oxygen is called the first or protoxide. 



296 CHEMICAL TRANSFORMATIONS. 

go that change; and combinations and decompo- 
sitions are the consequence. But when the atoms 
of the second body are not capable of such an action, 
any further disposition to change ceases from the 
moment at which the atoms of the first body assume 
the state of rest, that is, when the changes or trans- 
formations of this body are quite completed. 

This influence exerted by one compound upon the 
other, is exactly similar to that which a body in the 
act of <^ombustion exercises upon a combustible body 
in its vicinity ; with this difference only, that the 
causes which determine the participation and dura- 
tion of these conditions are different. For the cause, 
in the case of the combustible body, is heat, which 
is generated every moment anew; whilst in the phe- 
nomena of decomposition and combination which we 
are considering at present, the cause is a body in 
the state of chemical action, which exerts the de- 
composing influence only so long as this action 
continues. 

Numerous facts show, that motion alone exercises 
a considerable influence on chemical forces. Thus, 
the power of cohesion does not act in many saline 
solutions, even when they are fully saturated with 
salts, if they are permitted to cool whilst at- rest. 
In such a case, the salt dissolved in a liquid does not 
crystallize; but when a grain of sand is thrown into, 
the solution, or when it receives the slightest move- 
ment, the whole liquid becomes suddenly solid while 
heat is evolved. The same phenomenon happens 
with water, for this liquid may be cooled much under 
32° F. (0° C), if kept completely undisturbed, but 
solidifies in a moment when put in motion. 

The atoms of a body must in fact be set in motion 
before they can overcome the vis inertioi so as to ar- 
range themselves into certain forms. A dilute solution 
of a salt of potash mixed with tartaric acid yields no 
precipitate whilst at rest; but if motion is communi- 
cated to the solution by agitating it briskly, solid 
crystals of cream of tartar are deposited. A solu- 



FERMENTATION AND PUTREFACTION. 297 

tion of a salt of magnesia, also, which is not rendered 
turbid by the addition of phosphate of ammonia, de- 
posits the phosphate of magnesia and ammonia on 
those parts of the vessel touched with the rod em- 
ployed in stirring. 

In the processes of combination and decompo- 
sition under consideration, motion, by overcoming 
the vis ijierticB, gives rise immediately to another 
arrangement of the atoms of a body, that is, to the 
production of a compound which did not before 
exist in it. Of course these atoms must previously 
possess the power of arranging themselves in a cer- 
tain order, otherwise both friction and motion w^ould 
be without the smallest influence. 

The simple permanence in position of the atoms 
of a body, is the reason that so many compounds ap- 
pear to present themselves, in conditions, and with 
properties, different from those which they possess, 
when they obey the natural attractions of their atoms. 
Thus sugar and glass, when melted and cooled rapid- 
ly, are transparent, of a conchoidal fracture, and 
elastic and flexible to a certain degree. But the 
former becomes dull and opaque on keeping, and 
exhibits crystalline faces by cleavage, which belong 
to crystallized sugar. Glass assumes also the same 
condition, when kept soft by heat for a long period ; 
it becomes white, opaque, and so hard as to strike 
fire with steel. Now, in both these bodies, the com- 
pound molecules evidently have different positions 
in the two forms. In the first form their attraction 
did not act in the direction in which their power of 
cohesion was strongest. It is known, also, that when 
sulphur is melted and cooled rapidly by throwing it 
into cold water, it remains transparent, elastic, and 
so soft that it may be drawn out into long threads ; 
but that after a few hours or days, it becomes again 
hard and crystalline. 

The remarkable fact here is, that the amorphous 
sugar or sulphur returns again into the crystalline 
condition, without any assistance from an exterior- 



298 CHEMICAL TRANSFORMATIONS. 

cause ; a fact which shows, that their molecules have 
assumed another position, and that they possess, 
therefore, a certain degree of mobility, even in the 
condition of a solid. A very rapid transposition or 
transformation of this kind is seen in arragonite, a 
mineral which possesses exactly the same compo- 
sition as calcareous spar, but of which the hardness 
and crystalline form prove that its molecules are 
arranged in a different manner. When a crystal of 
arrago»ite is heated, an interior motion of its mole- 
cules is caused by the expansion ; the permanence 
of their arrangement is destroyed ; and the crystal 
splinters with much violence, and falls into a heap 
of small crystals of calcareous spar. 

It is impossible for us to be deceived regarding the 
causes of these changes. They are owing to a dis- 
turbance of the state of the equilibrium, in con- 
sequence of which the particles of the body put in 
motion obey other affinities or their own natural 
attractions. 

But if it is true, as we have just shown it to be, 
that mechanical motion is sufficient to cause a change 
of condition in many bodies, it cannot be doubted 
that a body in the act of combination or decompo- 
sition is capable of imparting the same condition of 
motion or activity in which its atoms are to certain 
other bodies : or in other words, to enable other 
bodies with which it is in contact to enter into com- 
binations, or suffer decompositions. 

The reality of this influence has been already suffi- 
ciently proved by the facts derived from inorganic 
chemistry, but it is of much more frequent occurrence 
in the relations of organic matter, and causes very 
striking and wonderful phenomena. 

By the iavms fermentatioji, putrefaction, and erema- 
causis, are meant those changes in form and prop- 
erties which compound organic substances undergo 
when separated from the organism, and exposed to 
the influence of water and a certain temperature. 
Fermentation and putrefaction are examples of that 



FERMENTATION AND PUTREFACTION. 299 

kind of decomposition, which we have named trans- 
formations : the elements of the bodies capable of 
undergoing these changes arrange themselves into 
new combinations, in which the constituents of water 
generally take a part. 

Eretnacausis (or decay) differs from fermentation 
and putrefaction, inasmuch as it cannot take place 
without the access of air, the oxygen of which is 
absorbed by the decaying bodies. Hence, it is a 
process of slow combustion, in which heat is uni- 
formly evolved, and occasionally even light. In the 
processes of decomposition termed fermentation and 
putrefaction, gaseous products are very frequently 
formed, which are either inodorous, or possess a very 
offensive smell. 

The transformations of those matters which evolve 
gaseous products without odor, are now, by pretty 
general consent, designated by the term fermenta- 
tion; whilst to the spontaneous decomposition of 
bodies which emit gases of a disagreeable smell, the 
term putrefaction is applied. But the smell is of 
course no distinctive character of the nature of the 
decomposition, for both fermentation and putrefac- 
tion are processes of decomposition of a similar kind, 
the one of substances destitute of nitrogen, the oth- 
er of substances which contain it. 

It has also been customary to distinguish from 
fermentation and putrefaction a particular class of 
transformations, viz., those in which conversions and 
transpositions are effected without the evolution of 
gaseous products. But the conditions under which 
the products of the decomposition present them- 
selves are purely accidental ', there is, therefore, no 
reason for the distinction just mentioned. 



300 CnE,-\IICAL TRAXSFORiMATIONS. 



CHAPTER III. 

FERMENTATION AND PUTREFACTION. 

Several bodies appear to enter spontaneously into 
the states of fermentation and putrefaction, particu- 
larly such as contain nitrogen or azotized substan- 
ces. Now, it is very remarkable, that very small 
quantities of these substances, in a state of fermenta- 
tion or putrefaction, possess the power of causing 
unlimited quantities of similar matters to pass into 
the same state. Thus, a small quantity of the juice 
of grapes in the act of fermentation, added to a 
large quantity of the same fluid, which does not fer- 
ment, induces the state of fermentation "in the whole 
mass. So likewise the most minute portion of milk, 
paste, juice of the beet-root, flesh, or blood, in the , 
state of putrefaction, causes fresh milk, paste, juice 
of the beet-root, flesh, or blood, to pass into the 
same condition when in contact with them. 

These changes evidently differ from the class of 
common decompositions which are effected by chem- 
ical affinity; they are chemical actions, conversions, 
or decompositions, excited by contact with bodies 
already in the same condition. In order to form a 
clear idea of these processes, analogous and less 
complicated phenomena must previously be studied. 

The compound nature of the mol'ecules of an or- 
ganic body, and the phenomena presented by them 
when in relation with other matters, point out the 
true cause of these transformations. Evidence is 
afforded even by simple bodies, that in the formation 
of combinations, the force with which the combining 
elements adhere to one another is inversely propor- 
tional to the number of simple atoms in the com- 
pound molecule. Thus, protoxide of manganese by 
absorption of oxygen is converted into the sesqui- 
oxide, the peroxide, manganic, and hypermanganic 



OF ORGANIC COMPOUNDS. 301 

acids, the number of atoms of oxygen being aug- 
mented by I, by 1, by 2, and by 5. But all the 
oxygen contained in these compounds, beyond that 
which belongs to the protoxide, is bound to the 
manganese by a much more feeble affinity ; a red 
heat causes an evolution of oxygen from the per- 
oxide, and the manganic and hypermanganic acids 
cannot be separated from their bases without under- 
going immediate decomposition. 

There are many facts which prove, that the most 
simple inorganic compounds are also the most stable, 
and undergo decomposition with the greatest diffi- 
culty, whilst those which are of a complex composi- 
tion yield easily to changes and decompositions. 
The cause of this evidently is, that, in proportion to 
the number of atoms which enter into a compound, 
the directions in which their attractions act will be 
more numerous. 

Whatever ideas we may entertain regarding the 
infinite divisibility of matter in general, the exist- 
ence of chemical proportions removes every doubt 
respecting the presence of certain limited groups or 
masses of matter which we have not the power of 
dividing. The particles of matter called equivalents 
in chemistry are not infinitely small, for they possess 
a weight, and are capable of arranging themselves 
in the most various ways, and of thus forming 
innumerable compound atoms. The properties of 
these compound atoms differ in organic nature, not 
only according to the form, but also in many instan- 
ces according to the direction and place, which the 
simple atoms take in the compound molecules. 

When we compare the composition of organic 
compounds with inorganic, we are quite amazed at 
the existence of combinations, in one single molecule 
of which, ninety or several hundred atoms or equiv- 
alents are united. Thus, the compound atom of an 
organic acid of very simple composition, acetic acid, 
for example, contains twelve equivalents of simple 
elements; one atom of kinovic acid contains 33, 1 
26 



302 CHEMICAL TRANSFORMATIONS. 

of sugar 36, 1 of amygdalin 90, and 1 of stearic 
acid 138 equivalents. The component parts of 
animal bodies are infinitely more complex even than 
these. 

Inorganic compounds differ from organic in as 
great a degree in their other characters as in their 
simplicity of constitution. Thus, the decomposition 
of a compound atom of sulphate of potash is aided 
by numerous causes, such as the power of cohesion, 
or the^capability of its constituents to form solid, 
insoluble, or at certain temperatures volatile com- 
pounds with the body brought into contact with it, 
and nevertheless a vast number of other substances 
produce in it not the slightest change. Now, in the 
decomposition of a complex organic atom, there is 
nothing similar to this. 

The empirical formula of sulphate of potash is 
SKO4.* It contains only 1 eq. of sulphur, and 1 eq. 
of potassium. We may suppose the oxygen to be 
differently distributed in the compound, and by a 
decomposition we may remove a part or all of it, or 
replace one of the constituents of the compound by 
another substance. But we cannot produce a differ- 
ent arrangement of the atoms, because they are 
already disposed in the simplest form in w^hich it is 
possible for them to combine. Now, let us compare 
the composition of sugar of grapes with the above : 
here 12 eq. of cai'bon, 12 eq. of hydrogen, and 12 eq. 
of oxygen, are united together, and we know that 
they are capable of combining with each other in 
the most various ways. From the formula of sugar, 
we might consider it either as a hydrate of carbon, 
wood, starch, or sugar of milk, or further, as a com- 
pound of ether with alcohol or of formic acid with 
sachulmin.f Indeed, we may calculate almost all 
the known organic compounds destitute of nitrogen 

* S denotes sulphur, K (Kali) potash, O oxygen, 4 the number of 
atoms. When no number is used, one atom is understood. 

i The black precipitate obtained hy the action of hydrochloric acid 
on susrar. 



OF ORGANIC COMPOUNDS. 303 

from sugar, by simply adding the elements of water, 
or by replacing any one of its elementary constitu- 
ents by a different substance. The elements neces- 
sary to form these compounds are, therefore, con- 
tained in the sugar, and they must also possess the 
power of forming numerous combinations amongst 
themselves by their mutual attractions. 

Now, when we examine what changes sugar under- 
goes when brought into contact with other bodies 
which exercise a marked influence upon it, we find, 
that these changes are not confined to any narrow 
limits, like those of inorganic bodies, but are in fact 
unlimited. 

The elements of sugar yield to every attraction, 
and to each in a peculiar manner. In inorganic 
compounds, an acid acts upon a particular constitu- 
ent of the body, which it decomposes, by virtue of 
its affinity for that constituent, and never resigns its 
proper chemical character, in whatever form it may 
be applied. But when it acts upon sugar, and 
induces great changes in that compound, it does 
this not by any superior affinity for a base existing 
in the sugar, but by disturbing the equilibrium in the 
mutual attraction of the elements of the sugar 
amongst themselves. Muriatic and sulphuric acids, 
which differ so much from one another both in char- 
acters and composition, act in the same manner upon 
sugar. But the action of both varies according to the 
state in which they arej thus they act in one way 
when dilute, in another when concentrated, and even 
differences in their temperature cause a change in 
their action. Thus sulphuric acid of a moderate 
degree of concentration converts sugar into a black 
carbonaceous matter, forming at the same time acetic 
and formic acids. But when the acid is more diluted, 
the sugar is converted into two brown substances, 
both of them containing carbon and the elements of 
water. Again, w^hen sugar is subjected to the action 
of alkalies, a whole series of different new products 
is obtained ; while oxidizing agents, such as nitric 



304 CHE?.IICAL TRANSFORMATIONS 

acid, produce from it carbonic acid, acetic acid, oxalic 
acid, formic acid, and many other products which 
have not yet been examined. 

If, from the facts here stated, we estimate the 
power with which the elements of sugar are united 
together, and judge of the force of their attraction 
by the resistance which they offer to the action of 
bodies brought into contact with them, we must 
regard the atom of sugar as belonging to that class 
of coin.pound atoms, which exist only by the vis 
inerticB of their elements. Its elements seem merely 
to retain passively the position and condition in 
which they had been placed, for we do not observe 
that they resist a change of this condition by their 
own mutual attraction, as is the case with sulphate 
of potash. 

Now it is only such combinations as sugar, com- 
binations, therefore, which possess a very complex 
molecule, which are capable of undergoing the de- 
compositions named fermentation and putrefaction. 

We have seen that metals acquire a power, which 
they do not of themselves possess, namely, that of 
decomposing water and nitric acid, by simple con- 
tact with other metals in the act of chemical combi- 
nation. We have also seen, that peroxide of hydro- 
gen and the persulphuret of the same element, in 
the act of decomposition, cause other compounds of 
a similar kind, but of which the elements are much 
more strongly combined, to undergo the same de- 
composition, although they exert no chemical affinity 
or attraction for them or their constituents. The 
cause which produces these phenomena will be also 
recognised, by attentive observation, in those matters 
which excite fermentation or putrefaction. All bod- 
ies in the act of combination or decomposition have 
the property of inducing those processes ; or, in 
other words, of causing a disturbance of the statical 
equilibrium in the attractions of the elements of 
complex organic molecules, in consequence of which 



OF BODIES WHICH DO NOT CONTMN NITROGEN. 305 

those elements group themselves anew, according to 
their special affinities. 

The proofs of the existence of this cause of action 
can be easily produced ; they are found in the char- 
acters of the bodies which effect fermentation and 
putrefaction, and in the regularity with which the 
distribution of the elements takes place in the sub- 
sequent transformations. This regularity depends 
exclusively on the unequal affinity which they possess 
for each other in an isolated condition. The action 
of water on wood, charcoal, and cyanogen, the sim- 
plest of the compounds of nitrogen, suffices to illus- 
trate the whole of the transformations of organic 
bodies ; of those in which nitrogen is a constituent, 
and of those in which it is absent. 



CHAPTER IV. 

ON THE TRANSFORMATION OF BODIES WHICH DO NOT CON- 
TAIN NITROGEN AS A CONSTITUENT, AND OF THOSE IN 
WHICH IT IS PRESENT. 

When oxygen and hydrogen combined in equal 
equivalents, as in steam, are conducted over char- 
coal, heated to the temperature at which it possesses 
the power to enter into combination with one of 
these elements, a decomposition of the steam ensues. 
An oxide of carbon (either carbonic oxide Or car- 
bonic acid) is under all circumstances formed, while 
the hydrogen of the water is liberated, or, if the 
temperature be sufficient, unites with the carbon, 
forming carburetted hydrogen. Accordingly, the 
carbon is shared between the elements of the water, 
the oxygen and hydrogen. Now a participation of 
this kind, but even more complete, is observed in 
every transformation, whatever be the nature of the 
causes by which it is effected. 
26* 



306 CHEMICAL TRANSFORMATIONS 

Acetic and meconic* acids suffer a true transform- 
ation under the influence of heat, that is, their com- 
ponent elements are disunited, and form new com- 
pounds without any of them being singly disen- 
gaged. Acetic acid is converted into acetone and 
carbonic acid (C4 H3 03= C3 H3 + C02), and 
meconic acid into carbonic acid and komenic acid ; 
whilst by the influence of a higher temperature, the 
latter is further decomposed into pyromeconic acid 
and carbonic acid. 

No\^in these cases the carbon of the bodies de- 
composed is shared between the oxygen and hydro- 
gen ; part of it unites with the oxygen and forms 
carbonic acid, whilst the other portion enters into 
combination with the hydrogen, and an oxide of a 
carbo-hydrogen is formed, in which all the hydrogen 
is contained. 

In a similar manner, when alcohol is exposed to a 
gentle red heat, its carbon is shared between the 
elements of the water, — an oxide of a carbo-hydro- 
gen which contains all the oxygen, and some gaseous 
compounds of carbon and hydrogen being produced. 

It is evident, that during transformations caused 
by heat, no foreign affinities can be in play, so that 
the new compounds must result merely from the 
elements arranging themselves, according to the 
degree of their mutual affinities, into new combina- 
tions, which are constant and unchangeable in the 
conditions under which they were originally formed, 
but undergo changes when these conditions become 
different. If we compare the products of two bod- 
ies, similar in composition but different in properties, 
which are subjected to transformations by two differ- 
ent causes, we find that the manner in which the 
atoms are transposed, is absolutely the same in 
both. 

In the transformation of wood in marshy soils, by 
what we call putrefaction, its carbon is shared 

* An acid existing in opium, and named from the Greek for poppy. 



OF BODIES CONTAINING NITROGEN. 307 

between the oxygen and hydrogen of its own sub- 
stance, and of the water, — carburetted hydrogen is 
consequently evolved, as well as carbonic acid, both 
of which compounds have an analogous composition 
(CH2, C02).* 

Thus also in that transformation of sugar, which 
is called fermentation, its elements are divided into 
two portions ; the one, carbonic acid, which contains 
§ of the oxygen of sugar ; and the other, alcohol, 
which contains all its hydrogen. 

In the transformation of acetic acid produced by 
a red heat, carbonic acid, which contains § of the 
oxygen of the acetic acid, is formed, and acetone, 
which contains all its hydrogen. 

It is evident from these facts, that the elements 
of a complex compound are left to their special 
attractions whenever their equilibrium is disturbed, 
from whatever cause this disturbance may proceed. 
It appears, also, that the subsequent distribution of 
the elements, so as to form new combinations, always 
takes place in the same way, with this difference 
only, that the nature of the products formed is 
dependent upon the number of atoms of the elements 
which enter into action ; or, in other words, that the 
products differ ad iiijinitum, according to the com- 
position of the original substance. 



ON THE TRANSFORMATION OF BODIES CONTAINING NITROGEN. 

When those substances are examined which are 
most prone to fermentation and putrefaction, it is 
found that they are all, without exception, bodies 
which contain nitrogen. In many of these com- 
pounds, a transposition of their elements occurs 
spontaneously as soon' as they cease to form a part 
of a living organism ; that is, when they are drawn 

* C carbon, H hydrogen, O oxygen. 



308 CHEMICAL TRANSFORJIATIONS 

out of the sphere of attraction in which alone they 
are able to exist. 

There are, indeed, bodies destitute of nitrogen, 
which possess a certain degree of stability only 
when in combination, but which are unknown in an 
isolated condition, because their elements, freed from 
the power by which they were held together, arrange 
themselves according to their own natural attrac- 
tions. Hypermanganic, manganic, and hyposulphu- 
rous af ids, belong to this class of substances, which 
however are rare. 

The case is very different with azotized bodies. 
It would appear that there is some peculiarity in the 
nature of nitrogen, which gives its compounds the 
power to decompose spontaneously with so much 
facility. Now, nitrogen is known to be the most 
indifferent of all the elements; it evinces no partic- 
ular attraction to any one of the simple bodies; and 
this character it preserves in all its combinations, a 
character which explains the cause of its easy sep- 
aration from the matters with which it is united. 

It is only when the quantity of nitrogen exceeds 
a certain limit, that azotized compounds have some 
degree of permanence, as is the case with melamin, 
ammelin, &c. Their liability to change is also dimin- 
ished, when the quantity of nitrogen is very small 
in proportion to that of the other elements with 
which it is united, so that their mutual attractions 
preponderate. 

This easy transposition of atoms is best seen in 
the fulminating silvers, in fulminating mercury, in 
the iodide or chloride of nitrogen, and in all fulmin- 
ating compounds. 

All other azotized substances acquire the same 
power of decomposition, when the elements of water 
are brought into play; and indeed, the greater part 
of them are not capable of transformation, while 
this necessary condition to the transposition of their 
atoms is absent. Even the compounds of nitrogen, 
which are most liable to change, such as those which 



OF BODIES CONTAINING NITROGEN. 309 

are found in animal bodies, do not enter into a state 
of putrefaction when dry. 

The result of the known transformations of azo- 
tized substances proves, that the water does not 
merely act as a medium in which motion is permitted 
to the elements in the act of transposition, but that 
its influence depends on chemical affinity. "When 
the decomposition of such substances is effected 
with the assistance of water, their nitrogen is in- 
variably liberated in the form of ammonia. This is 
a fixed rule without any exceptions, wJiatever may be 
the cause which produces the decompositions. All 
organic compounds containing nitrogen, evolve the 
whole of that element in the form of ammonia when 
acted on by alkalies. Acids, and increase of tempera- 
ture, produce the same effect. It is only when there is 
a deficiency of water or its elements, that cyanogen 
or other azotized compounds are produced. 

From these facts it may be concluded, that am- 
monia is the most stable compound of nitrogen; and 
that hydrogen and nitrogen possess a degree of 
affinity for each other surpassing the attraction of 
the latter body for any other element. 

Already, in considering the transformations of sub- 
stances destitute of nitrogen, we have recognised 
the great affinity of carbon for oxygen as a power- 
ful cause for effecting the disunion of the elements 
of a complex organic atom in a definite manner. But 
carbon is also invariably contained in azotized or- 
ganic compounds, while the great affinity of nitrogen 
for hydrogen furnishes a new and powerful cause, 
facilitating the transposition of their component 
parts. Thus, in the bodies which do not contain 
nitrogen we have one element, and in those in which 
that substance is present, two elements, w^hich mutu- 
ally share the elements of water. Hence there- are 
two opposite affinities at play, which mutually 
strengthen each other's action. 

Now we know, that the most powerful attractions 
may be overcome by the influence of two affinities. 



310 CHEMICAL TRANSFORMATIONS 

Thus, a decomposition of alumina may be effected 
with the greatest facility, when the affinity of char- 
coal for oxygen, and of chlorine for aluminium, are 
both put in action, although neither of these alone 
has any influence upon it. There is in the nature 
and constitution of the compounds of nitrogen a kind 
of tension of their component parts, and a strong 
disposition to yield to transformations, which effect 
spontaneously the transposition of their atoms on the 
instaQ.t that water or its elements are brought in 
contact with them. 

The characters of the hydrated cyanic acid, one 
of the simplest of all the compounds of nitrogen, are 
perhaps the best adapted to convey a distinct idea 
of the manner in which the atoms are disposed of in 
transformations. This acid contains nitrogen, hy- 
drogen, and oxygen, in such proportions, that the 
addition of a certain quantity of the elements of 
water is exactly sufficient to cause the oxygen con- 
tained in the water and acid to unite with the car- 
bon and form carbonic acid, and the hydrogen of the 
water to combine with the nitrogen and form am- 
monia. The most favorable conditions for a com- 
plete transformation are, therefore, associated in 
these bodies, and it is well known, that the disunion 
takes place on the instant in which the cyanic acid 
and water are brought into contact, the mixture being 
converted into carbonic acid and ammonia, with brisk 
effervescence. 

This decomposition may be considered as the type 
of the transformations of all azotized compounds; it 
is putrefaction in its simplest and most perfect form, 
because the new products, the carbonic acid and 
ammonia, are incapable of further transformations. 

Putrefaction assumes a totally different and much 
more complicated form, when the products, which are 
first formed, undergo a further change. In these 
cases the process consists of several stages, of which 
it is impossible to determine when one ceases and 
the other begins. 



OF BODIES CONTAININU NITKOGEN. 311 

The transformations of cyanogen, a body com- 
posed of carbon and nitrogen, and the simplest of all 
the compounds of nitrogen, will convey a clear idea 
of the great variety of products which are produced 
in such a case: it is the only example of the putre- 
faction of an azotized body which has been at all 
accurately studied. 

A solution of cyanogen in water becomes turbid 
after a short time, and deposits a black, or brownish 
black matter, which is a combination of ammonia 
with another body, produced by the simple union of 
cyanogen with water. This substance is insoluble 
in water, and is thus enabled to resist further change. 

A second transformation is effected by the cyano- 
gen being shared between the elements of the water, 
in consequence of which cyanic acid is formed by a 
certain quantity of the cyanogen combining with the 
oxygen of the water, while hydrocyanic acid is also 
formed by another portion of the cyanogen uniting 
with the hydrogen which w^as liberated. 

Cyanogen experiences a third transformation, by 
which a complete disunion of its elements takes 
place, these being divided between the constituents 
of the water. Oxalic acid is the one product of this 
disunion, and annnonia the other. 

Cyanic acid, the formation of which has been 
mentioned above, cannot exist in contact with water, 
being decomposed immediately into carbonic acid 
and ammonia. The cyanic acid, however, newly 
formed in the decomposition of cyanogen, escapes 
this decomposition by entering into combination with 
the free ammonia, by which urea * is produced. 

The hydrocyanic acid is also decomposed into a 
brown matter which contains hydrogen and cyano- 
gen, the latter in greater proportion than it does in 
the gaseous state. Oxalic acid, urea, and carbonic 
acid, are also formed by its decomposition, and form- 

* See page 87, note. 



312 CHEMICAL TRANSFORMATIONS. 

ic acid and ammonia are produced by the decompo- 
sition of its radical. 

Thus, a substance into the composition of Avhich 
only two elements (carbon and nitrogen) enter, yields 
eight totally different products. Several of these 
products are formed by the transformation of the 
original body, its elements being shared between the 
constituents of water; others are produced in con- 
sequence of a further disunion of those first formed. 
The\irea and carbonate of ammonia are generated 
by the combination of two of the products, and in 
their formation the whole of the elements have as- 
sisted. 

These examples show, that the results of decompo- 
sition by fermentation or putrefaction comprehend 
very different phenomena. The first kind of trans- 
formation is, the transposition of the elements of one 
complex compound, by which new compounds are 
produced with or without the assistance of the ele- 
ments of water. In the products newly formed in 
this manner, either the same proportions of those 
component parts which were contained in the mat- 
ter before transformation, are found, or with them, 
an excess, consisting of the constituents of water, 
which had assisted in promoting the disunion of the 
elements. 

The second kind of transformation consists of 
the transpositions of the atoms of two or more com- 
plex compounds, by which the elements of both 
arrange themselves mutually into new products, with 
or without the cooperation of the elements of water. 
In this kind of transformation, the new products 
contain the sum of the constituents of all the com- 
pounds which had taken a part in the decomposition. 

The first of these two modes of decomposition is 
that designated fermentation, the second putrefac- 
tion ; and when these terms are used in the following 
pages, it will always be to distinguish the two pro- 
cesses above described,, which are so different in 
their results. 



FERMENTATION OF SUGAK. 313 



CHAPTER V. 

FERMENTATION OF SUGAR. 

The peculiar decomposition, which sugar suffers, 
may be viewed as a type of all the transformations 
designated fermentation.* 

Thenard obtained from 100 grammes f of cane- 
sugar 0-5262 of absolute alcohol. 100 parts of sugar 
from the cane yield, therefore, 103-89 parts of car- 
bonic acid and alcohol. The entire carbon in these- 
products is equal to 42 parts, which is exactly the 
quantity originally contained in the sugar. 

The analysis of sugar fyom the cane, proves that 
it contains the elements of carbonic acid and alco- 
hol, miims 1 atom of water. The alcohol and car- 
bonic acid produced by the fermentation of a certain 
quantity of sugar, contained together one equivalent 
of oxygen, and one equivalent of hydrogen, the ele- 
ments, therefore, of one equivalent of water, more 
than the sugar contained. The excess of weight in 
the products is thus explained most satisfactorily; 
it is owing, namely, to the elements of water having 
taken part in the metamorphosis of the sugar. 

It is known, that 1 atom of sugar contains 12 
equivalents of carbon, both from the proportions in 
which it unites with bases, and from the composition 

* When yeast is made into a thin paste with water, and 1 cubic centi- 
metre of this mixture introduced into a graduated glass receiver filled 
with mercury, in which are already 19 grammes of a solution of cane- 
sugar, containing I gramme of pure solid sugar; it is found, after the 
mixture has been exposed for 24 hours to a temperature of from 20 to 
2o C. (68-77 F.), that a volume of carbonic acid has been formed, 
which, at 0° C. (32° F.) and an atmospheric pressure indicated by 0-7(5 
metre Bar. would be from 245 to 250 cubic centimetres. But to this 
quantity we must add 11 cubic centimetres of carbonic acid, with 
wiiich tlie 11 grammes of liquid would be saturated, so that in all 255 
-259 cubic centimetres of carbonic acid are obtained. This volume 
of carbonic acid corresponds to from 0-503 to 0-5127 grammes bv 
weight. — L. 

\ The gramme equals 15-4440 grains. 



314 FERMENTATION OF SUGAR. 

of saccharic acid, the product of its oxidation. Now 
none of these atoms of carbon are contained in the 
sugar as carbonic acid, because the whole quantity is 
obtained as oxalic acid, when sugar is treated with 
hypermanganate of potash (Gregory); and as oxalic 
acid is a lower degree of the oxidation of carbon 
than carbonic acid, it is impossible to conceive that 
the lower degree should be produced from the high- 
er, by means of one of the most powerful agents of 
oxidation which we possess. 

It can be also proved, that the .hydrogen of the 
sugar does not exist in it in the form of alcohol, for 
it is converted into water and a kind of carbona- 
ceous matter, when treated with acids, particularly 
with such as contain no oxygen ; and this manner 
of decomposition is never suffered by a compound 
of alcohol. 

Sugar contains, therefore, neither alcohol nor car- 
bonic acid, so that these bodies must be produced by 
a different arrangement of its atoms, and by their 
union with the elements of w^ater. 

In this metamorphosis of sugar, the elements of 
the yeast, by contact with which its fermentation 
was effected, take no appreciable part in the trans- 
position of the elements of the sugar; for in the 
products resulting from the action, we find no com- 
ponent part of this substance. 

We may now study the fermentation of a vegeta- 
ble juice, which contains not only saccharine matter, 
but also such substances as albumen and gluten. 
The juices of parsnips, beet-roots, and onions, are 
well adapted for this purpose. When such a juice 
is mixed with yeast at common temperatures, it fer- 
ments like a solution of suo-ar. Carbonic acid gas 
escapes from it with effervescence, and in the liquid, 
alcohol is found in quantity exactly corresponding to 
that of the sugar originally contained in the juice. 
But such a juice undergoes spontaneous decomposi- 
tion at a temperature of from 95° to 104° (35° — 40° 
C). Gases possessing an offensive smell are evolved 



YEAST OR FERMENT. 315 

in consideratjle quantity, and when the liquor is ex- 
amined after the decomposition is completed, no al- 
cohol can be detected. The sugar has also disap- 
peared, and with it all the azotized compounds which 
existed in the juice previously to its fermentation. 
Both were decomposed at the same time ; the nitro- 
gen of the azotized compounds remains in the liquid 
as ammonia, and, in addition to it, there are three 
new products, formed from the component parts of 
the juice. One of these is lactic acid, the slightly 
volatile compound found in the animal organism ; 
the other is the crystalline body, which forms the 
principal constituent of manna; and the third is a 
mass resembling gum-arabic, which forms a thick 
viscous solution with water. These three products 
weigh more than the sugar contained in the juice, 
even without calculating the weight of the gaseous 
products. Hence, they are not produced from the 
elements of the sugar alone. None of these three 
substances could be detected in the juice before fer- 
mentation. They must, therefore, have been formed 
by the interchange of the elements of the sugar with 
those of the foreign substances also present. It is 
this mixed transformation of two or more compounds 
w^hich receives the special name of putrefaction. 



YEAST OR FERMENT. 

When attention is directed to the condition of 
those substances, which possess the power of induc- 
ing fermentation and putrefaction in other bodies, 
evidences are found in their general characters, and 
in the manner in which they combine, that they all 
are bodies, the atoms of which are in the act of 
transposition. 

The characters of the remarkable matter, which is 
deposited in an insoluble state during the fermenta- 
tion of beer, wine, and vegetable juices, may first be 
studied. 



316 YEAST OR FERMENT. 

This substance, which has been called yeast ov fer- 
ment, from the power which it possesses of causing 
fermentation in sugar, or saccharine vegetable juices, 
possesses all the characters of a compound of 7iitro- 
gen in the state of putrefaction and eremacausis. 

Like wood in the state of eremacausis, yeast con- 
verts the oxygen of the surrounding air into carbon- 
ic acid, but it also evolves this gas from its own 
mass, like bodies in the state of putrefaction. (Colin.) 
Wher^kept under water, it emits carbonic acid, ac- 
companied by gases of an offensive smell, (Thenard,) 
and is at last converted into a substance resembling 
old cheese. (Proust.) But when its own putrefaction 
is completed, it has no longer the power of inducing 
fermentation in other bodies. The presence of wa- 
ter is quite necessary for sustaining the properties 
of ferment, for by simple pressure its power to ex- 
cite fermentation is much diminished, and is com- 
pletely destroyed by drying. Its action is arrested 
also by the temperature of boiling water, by alcohol, 
common salt, an excess of sugar, oxide of mercury, 
corrosive sublimate, pyroligneous acid, sulphurous 
acid, nitrate of silver, volatile oils, and in short by 
all antiseptic substances. 

The insoluble part of the substance called ferment 
does not cause fermentation. For when the yeast 
from wine or beer is carefully washed with water, 
care being taken that it is always covered with this 
fluid, the residue does not produce fermentation. 

The soluble part offerm^ent likeicise does 7iot excite 
fermentation. An aqueous infusion of yeast may be 
mixed with a solution of sugar, and preserved in 
vessels from which the air is excluded, without eith- 
er experiencing the slightest change. What then, 
we may ask, is the matter in ferment which excites 
fermentation, if neither the soluble nor insoluble 
parts possess the power ? This question has been 
answered by Colin in the most satisfactory manner. 
He has shown, that in reality it is the soluble part. 
But before it obtains this power, the decanted infu- 



ITS PROPERTIES. 317 

sion must be allowed to cool in contact with the air, 
and to remain some time exposed to its action. When 
introduced into a solution of sugar in this state, it 
produces a brisk fermentation ; but without previous 
exposure to the air, it manifests no such property. 

The infusion absorbs oxygen during its exposure 
to the air, and carbonic acid may be found in it after 
a short time. 

Yeast produces fermentation in consequence of the 
progressive decomposition, which it suffers from the 
action of air and water. 

Now when yeast is made to act on sugar, it is 
found, that after the transformation of the latter 
substance into carbonic acid and alcohol is com- 
pleted, part of the yeast itself has disappeared. 

From 20 parts of fresh yeast from beer, and 100 
parts of sugar, Thcnard obtained, after the fermen- 
tation was completed, 13-7 parts of an insoluble 
residue, which diminished to 10 parts when employed 
in the same way with a fresh portion of sugar. 
These ten parts were white, possessed of the prop- 
erties of woody fibre, and had no further action on 
sugar. 

It is evident, therefore, that during the fermenta- 
tion of sugar by yeast, both of these substances 
suffer decomposition at the same time, and disappear 
in consequence. But if yeast be a body which ex- 
cites fermentation by being itself in a state of de- 
composition, all other matters in the same condition 
should have a similar action upon sugar; and this is 
in reality the case. Muscle, urine, isinglass, osma- 
zorae,* albumen, cheese, gliadine, gluten, legumin, 
and blood, when in a state of putrefaction, have all 
the power of producing the putrefaction, or fermen- 
tation of a solution of sugar. Yeast, which by con- 
tinued washing has entirely lost the property of in- 
ducing fermentation, regains it when its putrefaction 

* An extractive animal matter on which the peculiar flavor of broth 
is supposed to depend ; hence its name, from the Greek for odor and 
broth. 

27* 



318 YEAST OF FERMENT. 

has recommenced, in consequence of its being kept in 
a warm situation for some time. 

Yeast and putrefying animal and vegetable mat- 
ters act as peroxide of hydrogen does on oxide of 
silver, when they induce bodies with which they are 
in contact to enter into the same state of decompo- 
sition. The disturbance in the attraction of the con- 
stituents of the peroxide of hydrogen effects a dis- 
turbance in the attraction of the elements of the 
oxide of silver, the one being decomposed, on ac- 
count of the decomposition of the other. 

Now if we consider the process of the fermentation 
of pure sugar, in a practical point of view, we meet 
with two facts of constant occurrence. When the 
quantity of ferment is too small in proportion to that 
of the sugar, its putrefaction^ will be completed before 
the transformation of all the sugar is effected. Some 
sugar here remains undecomposed, because the cause 
of its transformation is absent, viz. contact with a 
body in a state of decomposition. 

But when the quantity of ferment predominates, a 
certain quantity of it remains after all the sugar has 
fermented, its decomposition proceeding very slowly, 
on account of its insolubility in water. This residue 
of ferment is still able to induce fermentation, when 
introduced into a fresh solution of sugar, and retains 
the same power until it has passed through all the 
stages of its own transformation. Hence, a certain 
quantity of yeast is necessary in order to effect the 
transformation of a certain portion of sugar, not 
because it acts by its quantity in increasing any 
affinity, but because its influence depends solely on 
its presence, and its presence is necessary, until the 
last atom of sugar is decomposed. 

These facts and observations point out the ex- 
istence of a new cause, which effects combinations 
and decompositions. This cause is the action which 
bodies in a state of combination or decomposition 
exercise upon substances, the component parts of 
which are united together by a feeble affinity. This 



AZOTIZED MATTERS THE CAUSE OF PUTREFACTION. 319 

action resembles a peculiar power, attached to a 
body in the state of combination or decomposition, 
but exerting its influence beyond the sphere of its 
own attractions. We are now able to account satis- 
factorily for many known phenomena. 

A large quantity of hippuric acid may be obtained 
from the fresh urine of a horse, by the addition of 
muriatic acid; but when the urine has undergone 
putrefaction, no trace of it can be discovered. The 
urine of man contains a considerable quantity of 
urea; but when the urine putrefies, the urea entirely 
disappears. When urea is added to a solution of 
sugar in the state of fermentation, it is decomposed 
into carbonic acid and ammonia. No asparagin * 
can be detected in a putrefied infusion of asparagin, 
liquorice-root, or the root of marshmallow {^Althcea 
officinalis). 

It has already been mentioned, that the strong 
affinity of nitrogen for hydrogen, and that of carbon 
for oxygen, are the cause of the facility with which 
the elements of azotized compounds are disunited ; 
those affinities aiding each other, inasmuch as by 
virtue of them different elements of the compounds 
strive to take possession of the different elements 
of water. Now since it is found that no body desti- 
tute of nitrogen, possesses, when pure, the property 
of decomposing spontaneously whilst in contact with 
water, we must ascribe this property which azotized 
bodies possess in so eminent a degree, to something 
peculiar in the nature of the compounds of nitrogen, 
and to their constituting, in a certain measure, more 
highly organized atoms. 

Every azotized constituent of the animal or vege- 
table organism runs spontaneously into putrefaction, 
when exposed to moisture and a high temperature. 

Azotized matters are, accordingly, the only causes 
of fermentation and putrefaction in vegetable sub- 
stances. 

* A peculiar principle obtained from asparagus. See Brande's 
Chemistry, p. 1042. 



320 YEAST OR FERMENT. 

Putrefaction, on account of its effects, as a mixed 
transformation of many different substances, may be 
classed with the most powerful processes of deoxi- 
dation, by which the strongest affinities are over- 
come. 

When a solution of gypsum in water is mixed with 
a decoction of sawdust, or any other organic matter 
capable of putrefaction, and preserved in well-closed 
vessels, it is found after some time, that the solution 
contains no more sulphuric acid, but in its place car- 
bonic and free hydrosulphuric acid, between which 
the lime of the gypsum is shared. In stagnant water 
containing sulphates in solution, crystallized pyrites 
is observed to form on the decaying roots. 

Now we know, that in the putrefaction of wood 
under water, when air therefore is excluded, a part 
of its carbon combines with the oxygen of the water, 
as well as with the oxygen which the wood itself 
contains ; whilst its hydrogen and that of the de- 
composed water are liberated either in a pure state, 
or as carburetted hydrogen. The products of this 
decomposition are of the same kind as those genera- 
ted when steam is conducted over red-hot charcoal. 

It is evident, that if with the water a substance 
containing a large quantity of oxygen, such as sul- 
phuric acid, be also present, the matters in the state 
of putrefaction will make use of the oxygen of that 
substance as well as that of the water, in order to 
form carbonic acid ; and the sulphur and hydrogen 
being set free will combine whilst in the nascent 
state, producing hydrosulphuric acid, which will be 
again decomposed if metallic oxides be present ; and 
the results of this second decomposition will be water 
and metallic sulphurets. 

The putrefied leaves of woad {^Isatis tinctoria), in 
contact with indigo-blue, water, and alkalies, suffer 
further decomposition, and the indigo is deoxidized 
and dissolved. 

The mannite formed by the putrefaction of beet- 
roots and other plants which contain sugar, contains 



DIFFERENCE OF FERMENTATION AND PUTREFACTION. 321 

the same number of equivalents of carbon and hydro- 
gen as the sugar of grapes, but two atoms less of 
oxygen ; and it is highly probable that it is produced 
from sugar of grapes, contained in those plants, in 
precisely the same manner as indigo-blue is con- 
verted into deoxidized white indigo. 

During the putrefaction of gluten, carbonic acid 
and pure hydrogen gas are evolved ; phosphate, 
acetate, caseate, and lactate of ammonia being at 
the same time produced in such quantity, that the 
further decomposition of the gluten ceases. But 
when the supply of water is renewed, the decompo- 
sition begins again, and in addition to the salts just 
mentioned, carljonate of ammonia and a white crys- 
talline matter resembling mica (caseous oxide) are 
formed, together with hydrosulphate of ammonia, 
and a mucilaginous substance coagulable by chlorine. 
Lactic acid is almost always produced by the putre- 
faction of organic bodies. 

We may now compare fermentation and putrefac- 
tion with the decomposition which organic com- 
pounds suffer under the influence of a high tempera- 
ture. Dry distillation would appear to be a process 
of combustion or oxidation going on in the interior 
of a substance, in which a part of the carbon unites 
with all or part of the oxygen of the compound, 
while other new compounds containing a large pro- 
portion of hydrogen are necessarily produced. Fer- 
mentation may be considered as a process of com- 
bustion or oxidation of a similar kind, taking place 
in a liquid between the elements of the same 7natter, 
at a very slightly elevated temperature; and putre- 
faction as a process of oxidation, in which the oxy- 
gen of all the substances present comes into play. 



322 EREMACAUSIS OR DECAY. 



CHAPTER VI. 

EREMACAUSIS, OR DECAY, 

In organic nature, besides the processes of decom- 
position named fermentation and putrefaction, an- 
other and not less striking class of changes occurs, 
which bodies suffer from the influence of the air. 
This is the act of gradual combination of the com- 
bustible elements of a body with the oxygen of the 
air ; a slow combustion or oxidation, to which we 
shall apply the term of eremacausis. 

The conversion of wood into humus, the formation 
of acetic acid out of alcohol, nitrification, and numer- 
ous other processes, are of this nature. Vegetable 
juices of every kind, parts of animal and vegetable 
substances, moist sawdust, blood, &c., cannot be 
exposed to the air, without suffering immediately a 
progressive change of color and properties, during 
which oxygen is absorbed. These changes do not 
take place when w^ater is excluded, or when the 
substances are exposed to the temperature of 32°, 
and it has been observed that different bodies require 
different degrees of heat, in order to effect the 
absorption of oxygen, and, consequently, their ere- 
macausis. The property of suffering this change is 
possessed in the highest degree by substances con- 
taining nitrogen. 

When vegetable juices are evaporated by a gentle 
heat in the air, a brown or brownish-black substance 
is precipitated as a product of the action of oxygen 
upon them. This substance, which appears to pos- 
sess similar properties from whatever juice it is 
obtained, has received the name of extractive matter; 
it is insoluble or very sparingly soluble in water, but 
is dissolved with facility by alkalies. By the action 
of air on solid animal or vegetable matters, a similar 



EREMACAUSIS OR DECAY. 323 

pulverulent brown substance is formed, and is known 
by the name of humus. 

The conditions which determine the commence- 
ment of eremacausis are of various kinds. Many 
organic substances, particularly such as are mixtures 
of several more simple matters, oxidize in the air 
when simply moistened with water; others not until 
they' are subjected to the action of alkalies; but the 
greatest part of them undergo this state of slow 
combustion or oxidation, when brought in contact 
with other decaying matters. 

The eremacausis of an organic matter is retarded 
or completely arrested by all those substances which 
prevent fermentation or putrefaction. Mineral acids, 
salts of mercury, aromatic substances, empyreumatic 
oils, and oil of turpentine, possess a similar action 
in this respect. The latter substances have the 
same effect on decaying bodies as on phosphuretted 
hydrogen, the spontaneous inflammability of which 
they destroy. 

Many bodies which do not decay when moistened 
with water, enter into eremacausis when in contact 
with an alkali. Gallic acid, heematin,* and many 
other compounds, may be dissolved in water and yet 
remain unaltered ; but if the smallest quantity of a 
free alkali is present, they acquire the property of 
attracting oxygen, and are converted into a brown 
substance like humus, evolving very frequently at 
the same time carbonic acid. (Chevreul.) 

A very remarkable kind of eremacausis takes 
place in many vegetable substances, when they are 
exposed to the influence of air, water, and ammonia. 
They absorb oxygen very rapidly, and form splendid 
violet or red-colored liquids, as in the case of orcin 
and erythrin. They now contain an azotized sub- 
stance, not in the form of ammonia. 

All these facts show, that the action of oxygen 
seldom affects the carbon of decaying substances, 

* The coloring matter of logwood. 



324 EREMACAUSIS OR DECAY, 

and this corresponds exactly to what happens in 
combustion at high temperatures. It is well known, 
for example, that when no more oxygen is admitted 
to a compound of carbon and hydrogen than is suffi- 
cient to combine with its hydrogen, the carbon is not 
burned, but is separated as lampblack^* while, if 
the quantity of oxygen is not sufficient even to con- 
sume all the hydrogen, new compounds are forined, 
such as napthalinf and similar matters, which con- 
tain a smaller proportion of hydrogen than those 
compounds of carbon and hydrogen which previously 
existed in the combustible substance. 

There is no example of carbon combining directly 
with oxygen at common temperatures, but numerous 
facts show that hydrogen, in certain states of con- 
densation, possesses that property. Lampblack which 
has been heated to redness may be kept in contact 
with oxygen gas, without forming carbonic acid; 
but lampblack, impregnated with oils which contain 
a large proportion of hydrogen, gradually becomes 
warm, and inflames spontaneously. The spontaneous 
inflammabilitv of the charcoal used in the fabrication 
of gunpowder has been correctly ascribed to the 
hydrogen, which it contains in considerable quantity; 
for during its reduction to powder, no trace of 
carbonic acid can be detected in the air surrounding 
it ; it is not formed until the temperature of the mass 
has reached a red heat. The heat which produces 
the inflammation is, therefore, not caused by the 
oxidation of the carbon. 

The substances which undergo eremacausis may 
be divided into two classes. The first class compre- 
hends those substances which unite with the oxygen 
of the air, without evolving carbonic acid ; and the 
second, such a& emit carbonic acid by absorbing 
oxygen. 

When the oil of bitter almonds is exposed to the 

* As in the combustion of spirits of turpentine, now much employed, 
under various names, in lamps. 

t A substance obtained from coal tar. 



EXAMPLES OF. 325 

air, it absorbs two equivalents of oxygen, and is con- 
verted into benzoic acid; but half of the oxygen ab- 
sorbed combines w^ith the hydrogen of the oil, and 
forms water, vvrhich remains in union with the anhy- 
drous benzoic acid.* 

But, although it appears very probable that the 
oxygen acts primarily and principally upon hydro- 
gen, the most combustible constituent of organic 
matter in the state of decay ; still it cannot thence 
be concluded, that the carbon is quite devoid of the 
power to unite with oxygen, when every particle of 
it is surrounded with hydrogen, an element with 
which the oxygen combines with greater facility. 

We know, on the contrary, that although nitrogen 
cannot be made to combine with oxygen directly, yet 
it is oxidized and forms nitric acid, when mixed 
with a large quantity of hydrogen, and burned in 
oxygen gas. In this case its affinity is evidently 
increased by the combustion of the hydrogen, which 
is in fact communicated to it. It is conceivable, 
that in a similar manner, the carbon may be directly 
oxidized in several cases, obtaining from its con- 
tact with hydrogen in eremacausis a property which 
it does not itself possess at common temperatures. 
But the formation of carbonic acid during the ere- 
macausis of bodies containing hydrogen, must in 
most cases be ascribed to another cause. It appears 

* According to the experiments of Dobereiner, 100 parts of pyrogal- 
lic acid absorb ;!8-0!) parts of oxygen when in contact with ammonia 
and water ; the acid being changed in consequence of this absorption 
into a mouldy substance, which contains less oxygen than the acid it- 
self. It is evident, that the substance which is formed is not a higher 
oxide ; and it is found, on comparing the quantity of the oxygen ab- 
sorbed with that of the hydrogen contained in the acid, that they are 
exactly in the proportions for forming water. 

When colorless orcin is exposed together with ammonia to the con- 
tact of oxygen gas, the beautiful red-colored orcein is produced. Now, 
the only changes which take place here are, that the absorption of oxy- 
gen by the elements of orcin and ammonia causes the formation of 
water; 1 equivalent of orcin CI 8 H12 OS, and I equivalent of ammo- 
nia NH3, absorb ij equivalents of oxygen, and 5 equivalents of water 
are produced, the composition of orcein being C18 HIO 08 N. (Du- 
mas.) In this case it is evident, that the oxygen absorbed has united 
merely with the hydrogen. — L. 

28 



326 EREMACAUSIS OR DECAY. 

to be formed in a manner similar to the formation of 
acetic acid, by the eremacausis of saliculite of pot- 
ash.* 

An alkaline solution of haematin being exposed to 
an atmosphere of oxygen, 0*2 grm. absorb 28'6 cubic 
centimeters of oxygen gas in twenty-four hours, the 
alkali acquiring at the same time 6 cubic centimeters 
of carbonic acid. (Chevreul.) But these 6 cubic 
centimeters of carbonic acid contain only an equal 
volume of oxygen, so that it is certain from this ex- 
periment, that I of the oxygen absorbed have not 
united with the carbon. It is highly probable, that 
during the oxidation of the hydrogen, a portion of 
the carbon had united with the oxygen contained in 
the haematin, and had separated from the other ele- 
ments as carbonic acid. 

The experiments of De Saussure upon the decay 
of woody fibre show, that such a separation is quite 
possible. Moist woody fibre evolved one volume of 
carbonic acid for every volume of oxygen which it 
absorbed. It has just been mentioned, that carbonic 
acid contains its own volume of oxygen. Now, 
woody fibre contains carbon and the elements of 
water, so that the result of the action of oxygen 
upon it is exactly the same as if pure charcoal had 
combined directly with oxygen. But the characters 
of woody fibre show, that the elements of water are 
not contained in it in the form of water ; for, were 
this the case, starch, sugar, and gum must also be 
considered as hydrates of carbon. 

But if the hydrogen does not exist in woody fibre 
in the form of water, the direct oxidation of the car- 
bon cannot be considered as at all probable, without 
rejecting all the facts established by experiment re- 
garding the process of combustion at low tempera- 
tures. 



* This salt, when exposed to a moist atmosphere, absorbs 3 atoms of 
oxygen; melanic acid is produced, a body resembling humus, in conse- 
quence of the formation of which, the elements of 1 atom of acetic acid 
are separated from the saliculous acid. — L. 



FORMATION OF CARBONIC ACID. 327 

If we examine the action of oxygen upon a sub- 
stance containing a large quantity of hydrogen, such 
as alcohol, we find most distinctly, that the direct 
formation of carbonic acid is the last stage of its 
oxidation, and that it is preceded by a series of 
changes, the last of which is a complete combustion 
of the hydrogen. Aldehyde, acetic, formic, oxalic, 
and carbonic acids, form a connected chain of pro- 
ducts arising from the oxidation of alcohol ; and the 
successive changes which this fluid experiences from 
the action of oxygen may be readily traced in them. 
Aldehyde is alcohol mmvs hydrogen ; acetic acid is 
formed by the direct union of aldehyde with oxygen. 
Formic acid and water are formed by the union of 
acetic acid with oxygen. When all the hydrogen is 
removed from this formic acid, oxalic acid is pro- 
duced ; and the latter acid is converted into car- 
bonic acid by uniting with an additional portion of 
oxygen. All these products appear to be formed 
simultaneously, by the action of oxidizing agents on 
alcohol ; but it can scarcely be doubted, that the 
formation of the last product, the carbonic acid, does 
not take place until all the hydrogen has been ab- 
stracted. 

The absorption of oxygen by drying oils certainly 
does not depend upon the oxidation of their carbon ; 
for in raw nut-oil, for example, which was not free 
from mucilage and other substances, only twenty-one 
volumes of carbonic acid were formed for every 146 
volumes of oxygen gas absorbed. 

It must be remembered, that combustion or oxida- 
tion at low temperatures produces results quite simi- 
lar to combustion at high temperatures with limited 
access of air. The most combustible element of a 
compound, which is exposed to the action of oxygen, 
must become oxidized first, for its superior combus- 
tibility is caused by its being enabled to unite with 
oxygen at a temperature at which the other elements 
cannot enter into that combination ; this property 
having the same etFect as a greater affinity. 



328 EREMACAUSIS OR DECAY 

The combustibility of potassium is no measure of 
its affinity for oxygen ; we have reason to believe 
that the attraction of magnesium and aluminium for 
oxygen is greater than that of potassium for the 
same element ; but neither of those metals oxidizes 
either in air or water at common temperatures, whilst 
potassium decomposes water with great violence, 
and appropriates its oxygen. 

Phosphorus and hydrogen combine with oxygen at 
ordinary temperatures, the first in moist air, the 
second when in contact with finely-divided platinum; 
while charcoal requires a red heat before it can enter 
into combination with oxygen. It is evident, that 
phosphorus and hydrogen are more combustible 
than charcoal, that is, that their affinity for oxygen 
at common temperatures is greater ; and this is not 
the less certain, because it is found, that carbon in 
certain other conditions shows a much greater affini- 
ty for oxygen than either of those substances. 

In putrefaction, the conditions are evidently pres- 
ent, under which the affinity of carbon for oxygen 
comes into play; neither expansion, cohesion, nor 
the gaseous state, opposes it, whilst in eremacausis 
all these restraints have to be overcome. 

The evolution of carbonic acid, during the decay 
or eremacausis of animal or vegetable bodies which 
are rich in hydrogen, must accordingly be ascribed 
to a transposition of the elements or disturbance in 
their attractions, similar to that which gives rise to 
the formation of carbonic acid in the processes of 
fermentation and putrefaction. 

The eremacausis of such substances is, therefore, 
a decomposition analogous to the putrefaction of 
azotized bodies. For in these there are two affini- 
ties at play; the affinity of nitrogen for hydrogen, 
and that of carbon for oxygen, and both facilitate the 
disunion of the elements. Now there are two affini- 
ties also in action in those bodies which decay with 
the evolution of carbonic acid. One of these affini- 
ties is the attraction of the oxygen of the air for the 



OF BODIES DESTITUTE OF NITROGEN. 329 

hydrogen of the substance, which corresponds to the 
attraction of nitrogen for the same element ; and the 
other is the affinity of the carbon of the substance 
for its oxygen, which is constant under all circum- 
stances. 

When wood putrefies in marshes, carbon and oxy- 
gen are separated from its elements in the form of 
carbonic acid, and hydrogen in the form of carburet- 
ted hydrogen. But when wood decays or putrefies 
in the air, its hydrogen does not combine with car- 
bon, but with oxygen, for which it has a much great- 
er affinity at common temperatures. 

Now it is evident, from the complete similarity of 
these processes, that decaying and putrefying bodies 
can mutually replace one another in their reciprocal 
actions. 

All putrefying bodies pass into the state of decay, 
when exposed freely to the air, and all decaying mat- 
ters into that of putrefaction when air is excluded. 
All bodies, likewise, in a state of decay are capable 
of inducing putrefaction in other bodies in the same 
manner as putrefying bodies themselves do. 



CHAPTER VII. 

EREMACAUSIS OR DECAY OF BODIES DESTITUTE OE 
NITROGEN: FORMATION OF ACETIC ACID. 

All those substances which appear to possess the 
property of entering spontaneously into fermenta- 
tion and putrefaction, do not in reality suffer those 
changes without some previous disturbance in the 
attraction of their elements. Eremacausis always 
precedes fermentation and putrefaction, and it is not 
until after the absorption of a certain quantity of 
oxygen that the signs of a transformation in the in- 
terior of the substances show themselves. 
28* 



330 EREMACAUSIS OR DECAY 

It is a very general error to suppose that organic 
substances have the power of undergoing change 
spontaneously, without the aid of an extei'nal cause. 
When they are not in a state of change, it is neces- 
sary, before they can assume that state, that the ex- 
isting equilibrium of their elements should be dis- 
turbed ; and the most common cause of this distur- 
bance is undoubtedly the atmosphere which surrounds 
all bodies. 

The juices of the fruit or other part of a plant 
which very readily undergo decomposition, retain 
their properties unchanged as long as they are pro- 
tected from immediate contact with the air, that is, 
as long as the cells or organs in which they are con- 
tained resist the influence of the air. It is not until 
after the juices have been exposed to the air, and 
have absorbed a certain quantity of oxygen, that the 
substances dissolved in them begin to be decom- 
posed. 

The beautiful experiments of Gay-Lussac upon 
the fermentation of the juice of grapes, as well as 
the important practical improvements to which they 
have led, are the best proofs that the atmosphere 
possesses an influence upon the changes of organic 
substances. The juice of grapes which were ex- 
pressed under a receiver filled with mercury, so that 
air was completely excluded, did not ferment. But 
when the smallest portion of air was introduced, a 
certain quantity of oxygen became absorbed, and 
fermentation immediately began. Although the juice 
was expressed from the grapes in contact with air, 
under the conditions therefore necessary to cause its 
fermentation, still this change did not ensue when 
the juice was heated in close vessels to the tempera- 
ture of boiling water. When thus treated, it could 
be preserved for years without losing its property 
of fermenting. A fresh exposure to the air at any 
period caused it to ferment. 

Animal food of every kind, and even the most 
delicate vegetables, may be preserved unchanged if 



OF BODIES DESTITUTE OF NITROGEN. 331 

heated to the temperature of boiling water in vessels 
from which the air is completely excluded. Food 
thus prepared has been kept for fifteen years, and 
upon opening the vessels, after this long time, has 
been found as fresh and well-flavoured as when origi- 
nally placed in them.* 

The action of the oxygen in these processes of 
decomposition is very simple ; it excites changes in 
the composition of the azotized matters dissolved in 
the juices, — the mode of combination of the elements 
of those matters undergoes a disturbance and change 
in consequence of their contact with oxygen. The 
oxygen acts here in a similar manner to the friction 
or motion which affects the mutual decomposition of 
two salts, the crystallization of salts from their 
solution, or the explosion of fulminating mercury. 
It causes the state of rest to be converted into a 
state of motion. 

When this condition of intestine motion is once 
excited, the presence of oxygen is no longer neces- 
sary. The smallest particle of an azotized body in 
this act of decomposition exercises an influence upon 
the particles in contact with it, and the state of 
motion is thus propagated through the substance. 
The air may now be completely excluded, but the 

* The process is as follows : Let the substance to be preserved be 
first parboiled, or rather somewhat more, the bones of the meat being 
previously removed Put the meat into a tin cylinder, fill up the 
vessel with seasoned rich soup, and then solder on the lid, pierced 
with a small hole. When this has been done, let the tin vessel thus 
prepared be placed in brine and heated to the boiling point, to com- 
plete the cooking of the meat. The hole of the lid is now to be closed 
by solderintr, whilst the air is rarefied. The vessel is then allowed to 
cool, and from the diminution of volume, in consequence of the re- 
duction of temperature, both ends of the cylinder are pressed inwards 
and become concave. The tin cases, thus hermetically sealed, are ex- 
posed in a test-chamber, for at least a month, to a temperature above 
what they are ever likely to encounter; from 9U° to 110° F. If the 
process has failed, putrefaction takes place, and gas is evolved, which 
will cause the ends of the case to bulge, so as to render them convex, 
instead of concave. But the contents of those cases which stand the 
test will infallibly keep perfectly sweet and good in any climate, and 
for any number of years. If there be any taint about the meat when 
put up, it inevitably ferments, and is detected in the proving process. 
— Urk's Diet, of.^rts and Manuf. 



332 EREMACAUSIS OR DECAY 

fermentation or putrefaction proceeds uninterrupted- 
ly to its completion. It has been remarked, that the 
mere contact of carbonic acid is sufficient to produce 
fermentation in the juices of several fruits. 

The contact of ammonia and alkalies in general 
may be mentioned amongst the chemical conditions, 
which determine the commencement of eremacausis ; 
for their presence causes many substances to absorb 
oxygen and to decay, in which neither oxygen nor 
alkalies alone produce that change. 

Thus alcohol does not combine with the oxygen 
of the air at common temperatures. But a solution 
of potash in alcohol absorbs oxygen with much 
rapidity, and acquires a brown color. The alcohol is 
found after a short time to contain acetic acid, form- 
ic acid, and the products of the decomposition of 
aldehyde by alkalies, including aldehyde resin, which 
gives the liquid a brown color. 

The most general condition for the production of 
eremacausis in organic matter is contact with a body 
already in the state of eremacausis or putrefaction. 
We have here an instance of true contagion ; for 
the communication of the state of combustion is in 
realit}^ the effect of the contact. 

It is decaying wood which causes fresh wood around 
it to assume the same Qondition, and it is the very 
finely divided woody fibre in the act of decay which 
in moistened gall-nuts converts the tannic acid with 
such rapidity into gallic acid. 

A most remarkable and decided example of this 
induction of combustion has been observed by De 
Saussure. It has already been mentioned, that moist 
woody fibre, cotton, silk, or vegetable mould, in the 
act of fermentation or putrefaction, converts oxygen 
gas which may surround it into carbonic acid, with- 
out change of volume. Now, De Saussure added 
a certain quantity of hydrogen gas to the oxygen, 
and observed a diminution in volume immediately 
after the addition. A part of the hydrogen gas had 
disappeared, and along with it a portion of the oxy- 



OF BODIES DESTITUTE OF NITROGEN. 333 

gen, but a corresponding quantity of carbonic acid 
gas had not been formed. The hydrogen and oxy- 
gen had disappeared in exactly the same proportion 
as that in which they combine to form water ; a true 
combustion of the hydrogen, therefore, had been in- 
duced by mere contact with matter in the state of 
eremacausis. The action of the decaying substance 
here produced results exactly similar to those effect- 
ed by spongy platinum ; but that they proceeded 
from a different cause was shown by the fact that 
the }iresence of carbonic oxide, which arrests com- 
pletely the action of platinum on carburetted hydro- 
gen, did not retard in the slightest degree the com- 
bustion of the hydrogen in contact with the decaying 
bodies. 

But the same bodies were found by De Saussure 
not to possess the property just described, before 
they were in a state of fermentation or decay ; and 
he has shown that' even when they are in this state, 
the presence of antiseptic matter destroys completely 
all their influence. 

Let us suppose a volatile substance containing a 
large quantity of hydrogen to be substituted for the 
hydrogen gas in De Saussure's experiments. Now, 
the hydrogen in such compounds being contained in 
a state of greater condensation would suffer a more 
rapid oxidation, that is, its combustion would be 
sooner completed. This principle is in reality at- 
tended to in the manufactories in which acetic acid 
is prepared according to the new plan. In the pro- 
cess there adopted all the conditions are afforded 
for the eremacausis of alcohol, and for its consequent 
conversion into acetic acid. 

The alcohol is exposed to a moderate heat, and 
spread over a very extended surface, but these con- 
ditions are not sufficient to effect its oxidation. 
The alcohol must be mixed with a substance which 
is with facility changed by the oxygen of the air, 
and either enters into eremacausis by mere contact 
with oxygen, or by its fermentation or putrefaction 



334 EREMACAUSIS OR DECAY 

yields products possessed of this property. A small 
quantity of beer, acescent wine, a decoction of malt, 
honey, and numerous other substances of this kind, 
possess the action desired. 

The difference in the nature of the substances 
which possess this property shows, that none of 
them can contain a peculiar matter which has the 
property of exciting eremacausis ; they are only the 
bearers of an action, the influence of which extends 
beyond the sphere of its own attractions. Their 
power consists in a condition of decomposition or 
eremacausis, which impresses the same condition 
upon the atoms of alcohol in its vicinity; exactly as 
in the case of an alloy of platinum and silver dis- 
solving in nitric acid, in which the platinum becomes 
oxidized, by virtue of an inductive action exercised 
upon it by the silver in the act of its oxidation. 
The hydrogen of the alcohol is oxidized at the 
expense of the oxygen in contact with it, and forms 
water, evolving heat at the same time ; the residue 
is aldehyde, a substance which has as great an affin- 
ity for oxygen as sulphurous acid, and combines, 
therefore, directly with it, producing acetic acid. 



CHAPTER VIII. 

EREMACAUSIS OF SUBSTANCES CONTAINING NITROGEN. 
NITRIFICATION. 

When azotized substances are burned at high 
temperatures, their nitrogen does not enter into 
direct combination with oxygen. The knowledge 
of this fact is of assistance in considering the pro- 
cess of the eremacausis of such substances. Azotized 
organic matter always contains carbon and hydrogen, 
both of which elements have a very strong affinity 
for oxygen. 

Now nitrogen possesses a very feeble affinity for 



OF BODIES CONTAINING NITROGEN. 335 

that element, so that its compounds during their 
combustion present analogous phenomena to those 
which are observed in the combustion of substances 
containing a large proportion of hydrogen and car- 
bon ; a separation of the carbon of the latter sub- 
stances in an uncornbined state takes place, and in 
the same way the substances containing nitrogen 
give out that element in its gaseous form. 

When a moist azotized animal matter is exposed 
to the action of the air, ammonia is always liberated; 
nitric acid is never formed. 

But when alkalies or alkaline bases are present, a 
union of oxygen with the nitrogen takes place under 
the same circumstances, and nitrates are formed 
together with the other products of oxidation. 

Although we see the most simple means and direct 
methods employed in the great processes of decom- 
position which proceed in nature, still we find that 
the final result depends on a succession of actions, 
which are essentially influenced by the chemical 
nature of the bodies submitted to decomposition. 

When it is observed that the character of a sub- 
stance remains unaltered in a whole series of phe- 
nomena, there is no reason to ascribe a new charac- 
ter to it, for the purpose of explaining a single 
phenomenon, especially where the explanation of 
that according to known facts offers no difficulty. 

The most distinguished philosophers suppose that 
the nitrogen in an animal substance, when exposed 
to the action of air, water, and alkaline bases, 
obtains the power to unite directly with oxygen, and 
form nitric acid, but we are not acquainted with a 
single fact which justifies this opinion. .It is only 
by the interposition of a large quantity of hydrogen 
in the state of combustion or oxidation, that nitro- 
gen can be converted into an oxide. 

When a compound of nitrogen and carbon, such 
as cyanogen, is burned in oxygen gas, its carbon 
alone is oxidized; and when it is conducted over a 
metallic oxide heated to redness, an oxide of nitro- 



336 EREMACAUSIS OR DECAY 

gen is very rarely produced, and never when the 
carbon is in excess. Kuhhnann found in his experi- 
ments, that it was only when cyanogen was mixed 
with an excess of oxygen gas, and conducted over 
spongy platinum, that nitric acid was generated. 

Kuhlmann could not succeed in causing pure nitro- 
gen to combine directly with oxygen, even under 
the most favorable circumstances; thus, with the 
aid of spongy platinum at different temperatures, no 
union took place. 

The carbon in the cyanogen gas must, therefore, 
have given rise to the combustion of the nitrogen by 
induction. 

On the other hand we find that ammonia (a com- 
pound of hydrogen and nitrogen) cannot be exposed 
to the action of oxygen, without the formation of an 
oxide of nitrogen, and in consequence the production 
of nitric acid. 

It is owing to the great facility with which ammo- 
nia is converted into nitric acid, that it is so difficult 
to obtain a correct determination of the quantity of 
nitrogen in a compound subjected to analysis, in 
which it is either contained in the form of ammonia, 
or from which ammonia is formed by an elevation of 
temperature. For w^hen ammonia is passed over 
red-hot oxide of copper, it is converted, either com- 
pletely or partially, into binoxide of nitrogen. 

When ammoniacal gas is conducted over peroxide 
of manganese or iron heated to redness, a large 
quantity of nitrate of ammonia is obtained, if the 
ammonia be in excess ; and the same decomposition 
happens when ammonia and oxygen are together 
passed over red-hot spongy platinum. 

It appears, therefore, that the combination of 
oxygen with nitrogen occurs rarely during the com- 
bustion of compounds of the latter element with 
carbon, but that nitric acid is always a product when 
ammonia is present in the substance exposed to 
oxidation. 

The cause wherefore the nitrogen in ammonia 



OF BODIES CONTAINING NITROGEN. 337 

exhibits such a strong disposition to become con- 
verted into nitric acid is, undoubtedly, that the two 
products, which are the result of the oxidation of 
the constituents of ammonia, possess the power of 
uniting with one another. Now this is not the case 
in the combustion of compounds of carbon and 
nitrogen; here one of the products is carbonic acid, 
which, on account of its gaseous form, must oppose 
the combination of the oxygen ^and nitrogen, by 
preventing their mutual contact, while the superior 
affinity of its carbon for the oxygen during the act 
of its formation will aid this effect. 

When sufficient access of air is admitted during 
the combustion of ammonia, water is formed as well 
as nitric acid, and both of these bodies combine 
together. The presence of water may, indeed, be 
considered as one "of the conditions essential to 
nitrification, since nitric acid cannot exist without it. 

Eremacausis is a kind of putrefaction, differing 
from the common process of putrefaction, only in 
the part which the oxygen of the air plays in the 
transformations of the body in decay. When this is 
remembered, and when it is considered that in the 
transposition of the elements of azotized bodies 
their nitrogen assumes the form of ammonia, and 
that in this form, nitrogen possesses a much greater 
disposition to unite with oxygen than it has in any of 
its other compounds ; we can with difficulty resist the 
conclusion, that ammonia is the general cause of 
nitrification on the surface of the earth, 

Azotized animal matter is not, therefore, the im- 
mediate cause of nitrification; it contributes to the 
production of nitric acid only in so far as it is a 
slow and continued source of ammonia. 

Now it has been shown in the former part of this 
work, that ammonia is always present in the atmo- 
sphere, so that nitrates might thence be formed in 
substances which themselves contained no azotized 
matter. It is known, also, that porous substances 
possess generally the power of condensing ammonia; 
29 



338 VINOUS FERMENTATION. 

there ftre few ferruginous earths which do not evolve 
ammoniacal products when heated to redness, and 
ammonia is the cause of the peculiar smell perceived 
upon moistening aluminous minerals. Thus, ammo- 
nia, by being a constituent of the atmosphere, is a 
very widely diffused cause of nitrification, which 
w^ill come into play whenever the different conditions 
necessary for the oxidation of ammonia are com- 
bined. It is probable, that other organic bodies in 
the state of eremacausis are the means of causing 
the combustion of ammonia; at all events, the cases 
are very rare, in which nitric acid is generated from 
ammonia, in the absence of all matter capable of 
eremacausis. 

From the preceding observations on the causes of 
fermentation, putrefaction, and decay, we may now 
draw several conclusions calculated to correct the 
views generally entertained respecting the fermenta- 
tion of wine and beer, and several other important 
processes of decomposition which occur in nature. 



CHAPTER IX. 

ON VINOUS FERMENTATION: — V^^INE AND BEER. 

It has already been mentioned, that fermentation 
is excited in the juice of grapes by the access of air; 
alcohol and carbonic acid being formed by the de- 
composition of the sugar contained in the fluid. But 
it was also stated, that the process once commenced, 
continues until all the sugar is completely decom- 
posed, quite independently of any further influence 
of the air. 

In addition to the alcohol and carbonic acid formed 
by the fermentation of the juice, there is also pro- 
duced a yellow or gray insoluble substance, contain- 
ing a large quantity of nitrogen. It is this body 
which possesses the power of inducing fermentation 



YEAST FROM BEER AND WINE. 339 

in a new solution of sugar, and which has in conse- 
quence received the name oi ferment. 

The alcohol and carbonic acid are produced from 
the elements of the sugar, and the ferment from those 
azotized constituents of the grape-juice, which have 
been termed gluten, or vegetable albumen. 

According to the experiments of De Saussure, 
fresh impure gluten evolved, in five weeks, twenty- 
eight times its volume of a gas which consisted | of 
carbonic acid, and | of pure hydrogen gas ; ammo- 
niacal salts of several organic acids were formed at 
the same time. Water must, therefore, be decom- 
posed during the putrefaction of gluten ; the oxygen 
of this water must enter into combination with some 
of its constituents, whilst hydrogen is liberated, a 
circumstance which happens only in decompositions 
of the most energetic kind. Neither ferment nor 
any substance similar to it is formed in this case; 
and we have seen that in the fermentation of sac- 
charine vegetable juices, no escape of hydrogen gas 
takes place. 

It is evident, that the decomposition which gluten 
suffers in an isolated state, and that which it under- 
goes when dissolved in a vegetable juice, belong to 
two different kinds of transformations. There is 
reason to believe, that its change to the insoluble 
state depends upon an absorption of oxygen, for its 
separation in this state may be effected, under cer- 
tain conditions, by free exposure to the air, without 
the presence of fermenting sugar. It is known also 
that the juice of grapes, or vegetable juices in gen- 
eral, become turbid when in contact with air, before 
fermentation commences; and this turbidness is owing 
to the formation of an insoluble precipitate of the 
same nature as ferment. 

From the phenomena which have been observed 
during the fermentation of wort,* it is known wdth 

* Wort is an infusion of malt; it consists of the soluble parts of this 
substance dissolved in water. — Ed. 



340 VINOUS FERMENTATION. 

perfect certainty, that ferment is formed from gluten 
at the same time that the transformation of the sugar 
is effected; for the wort contains the azotized mat- 
ter of the corn, namely, gluten in the same condition 
as it exists in the juice of grapes. The wort fer- 
ments by the addition of yeast, but after its decora- 
position is completed, the quantity of ferment or 
yeast is found to be thirty times greater than it was 
originally. 

Yeast from beer and that from wine, examined un- 
der the microscope, present the same form and gen- 
eral appearance. They are both acted on in the 
same manner by alkalies and acids, and possess the 
power of inducing fermentation anew in a solution 
of sugar; in short, they must be considered as 
identical. 

The fact that water is decomposed during the pu- 
trefaction of gluten has been completely proved. The 
tendency of the carbon of the gluten to appropriate 
the oxygen of water must also always be in action, 
whether the gluten is decomposed in a soluble or in- 
soluble state. These considerations, therefore, as well 
as the circumstance which all the experiments made 
on this subject appear to point out, that the conver- 
sion of gluten to the insoluble state is the result of 
oxidation, lead us to conclude, that the oxygen con- 
sumed in this process is derived from the elements 
of water, or from the sugar w^hich contains oxygen 
and hydrogen in the same proportion as water. At 
all events, the oxygen thus consumed in the fermen- 
tation of wine and beer is not taken from the at- 
mosphere. 

The fermentation of pure sugar in contact with 
yeast must evidently be a very different process from 
the fermentation of wort or tnust* 

In the former case, the yeast disappears during 
the decomposition of sugar; but in the latter, a 
transformation of gluten is effected at the same time, 

"* The liquid expressed from grapes when fully ripe is called must. 



OILY AND ETHEREAL PRODUCTS. 341 

by which ferment is generated. Thus yeast is de- 
stroyed in the one case, but is formed in the other. 

Now since no free hydrogen gas can be detected 
during the fermentation of beer and wine, it is evi- 
dent that the oxidation of the gluten, that is, its 
conversion into ferment, must take place at the cost 
either of the oxygen of the water, or of that of the 
sugar ; whilst the hydrogen which is set free must 
enter into new combinations, or by the deoxidation 
of the sugar, new compounds containing a large pro- 
portion of hydrogen, and small quantity of oxygen, 
together with the carbon of the sugar, must be 
formed. 

It is well known, that wine and fermented liquors 
generally contain, in addition to the alcohol, other 
substances which could not be detected before their 
fermentation, and which must have been formed, 
therefore, during that process in a manner similar to 
the production of mannite. The smell and taste 
which distinguish wune from all other fermented 
liquids are known to depend upon an ether of a vol- 
atile and highly combustible acid ; the ether is of an 
oily nature, and has received the name (Enajithic 
ether. It is also ascertained, that the smell and 
taste of brandy from corn and potato are owing to a 
peculiar oil, the oil of potatoes. This oil is more 
closely allied to alcohol in its properties, than to 
any other organic substance. 

These bodies are products of the deoxidation of 
the substances dissolved in the fermenting liquids ; 
they contain less oxygen than sugar or gluten, but 
are remarkable for the large quantity of hydrogen 
which enters into their composition. 

GEnanthic acid contains an equal number of equiv- 
alents of carbon and hydrogen, exactly the same 
proportions of these elements, therefore, as sugar, 
but by no means the same proportion of oxygen. 
The oil of potatoes contains much more hydrogen. 

Although it cannot be doubted, that these volatile 
liquids are formed by a mutual interchange of the 
29* 



342 \TNOUS FERMENTATION. 

elements of gluten and sugar, in consequence, there- 
fore, of a true process of putrefaction, still it is cer- 
tain, that other causes exercise an influence upon 
their production and peculiarities. 

The substances in wine to which its taste and 
smell are owing, are generated during the fermenta- 
tion of the juice of such grapes as contain a certain 
quantity of tartaric acid ; they are not found in 
wines which are free from all acid, or which contain 
a different organic acid, such as acetic acid. 

The wines of warm climates possess no odor ; 
wines grown in France have it in a marked degree, 
but in the wines from the Rhine the perfume is most 
intense. The kinds of grapes on the Rhine, which 
ripen very late, and scarcely ever completely, such 
as the Riessling and Orleans, have the strongest 
perfume or bouquet, and contain, proportionally, a 
larger quantity of tartaric acid. The earlier grapes, 
such as the Rulander, and others, contain a large 
proportion of alcohol, and are similar to Spanish 
wines in their flavor, but they possess no bouquet. 

The grapes grown at the Cape from Riesslings 
transplanted from the Rhine, produce an excellent 
wine, which does not, however, possess the aroma 
which distinguishes Rhenish wine. 

It is evident from these facts, that the acid of 
wines, and their characteristic perfumes, have some 
connexion, for they are always found together ; and 
it can scarcely be doubted, that the presence of the 
former exercises a certain influence on the formation 
of the latter. This influence is very plainly observ- 
ed in the fermentation of liquids, which are quite 
free from tartaric acid, and particularly of those 
which are nearly neutral or alkaline, such as the 
mash* of potatoes or corn. 

The brandy obtained from corn and potatoes con- 
tains an ethereal oil, of a similar composition in both, 



* Mash is the mixture of malt, potatoes, and water, in the mash tun, 

a large vessel in which it is infused. 



OILY AND ETHEREAL PRODUCTS. 343 

to which these liquors owe their peculiar smell. This 
oil is generated during the fermentation of the mash ; 
it exists ready formed in the fermented liquids, and 
distils over with alcohol, when a gentle heat is 
applied. 

It is observed, that a greater quantity of alcohol is 
obtained when the mash is made quite neutral by- 
means of ashes or carbonate of lime, but that the 
proportion of oil in the brandy is also increased. 

Now it is known, that brandy made from potato 
starch, which has been converted into sugar by di- 
lute sulphuric acid, is completely free from the po- 
tato oil, so that this substance must be generated in 
consequence of a change suffered by the cellular 
tissue of the potatoes during their fermentation. 

Experience has shown, that the simultaneous fer- 
mentation or putrefaction of the cellular tissue, by 
which this oil is generated, may be completely pre- 
vented in the fabrication of brandy from corn.* 

The same malt, which in the preparation of brandy 
yields a fluid containing the oil of which w^e are 
speaking, affords in the formation of beer a spiritu- 
ous liquor, in which no trace of that oil can be de- 
tected. The principal difference in the preparation 
of the two liquids is, that in the fermentation of wort, 
an aromatic substance (hops) is added, and it is cer- 
tain that its presence modifies the transformations 
which take place. Now it is known that the volatile 
oil of mustard, and the empyreumatic oils, arrest 
completely the action of yeast ; and although the oil 
of hops does not possess this property, still it di- 
minishes, in a great degree, the influence of decom- 
posing azotized bodies upon the conversion of alco- 
hol into acetic acid. There is, therefore, reason to 
believe that some aromatic substances, when added 
to fermenting mixtures, are capable of producing very 

* In the manufactory of M. Dubrunfaut, so considerable a quantity 
of this oil is obtained under certain circumstances from brandy made 
from potatoes, that it might be employed for the purpose of illuminating 
his whole manufactory. — L. 



344 VINOUS FERMENTATION. 

various modifications in the nature of the products 
generated. 

Whatever opinion, however, may be held regard- 
ing the origin of the volatile odoriferous substances 
obtained in the fermentation of wine, it is quite cer- 
tain that the characteristic smell of wine is owing 
to an ether of an organic acid, resembling one of the 
fatty acids (cenanthic ether). 

It is only in liquids which contain other very solu- 
ble acids, that the fatty acids and cenanthic acids are 
capable of entering into combination with the ether 
of alcohol, and of thus producing compounds of a 
peculiar smell. This ether is found in all wines 
which contain free acid, and is absent from those in 
which no acids are present. This acid, therefore, is 
the m.eans by which the smell is produced ; since 
without its presence cenanthic ether could not be 
formed. 

The greatest part of the oil of brandy made from 
corn consists of a fatty acid not converted into 
ether; it dissolves oxide of copper and metallic ox- 
ides in general, and combines with the alkalies. 

The principal constituent of this oil is an acid 
identical in composition with cenanthic acid, but 
different in properties. (Mulder.) It is formed in 
fermenting liquids, which, if they be acid, contain 
only acetic acid, a body which has no influence in 
causing other acids to form ethers. 

The oil of brandy made from potatoes is the .hy- 
drate of an organic base analogous to ether, and 
capable, therefore, of entering into combination with 
acids. It is formed in considerable quantity in fer- 
menting liquids which are slightly alkaline; under 
circumstances, consequently, in which it is incapable 
of combining with an acid. 

The products of the fermentation and putrefaction 
of neutral vegetable and animal matters are gener- 
ally accompanied by substances of an offensive odor; 
but the most remarkable example of the generation 
of a true ethereal oil is seen in the fermentation of 



ODORIFEROUS PRODUCTS. 345 

the Herha centaurium niinorius, a plant which pos- 
sesses no smell. When it is exposed in water to a 
slightly elevated temperature it ferments, and emits 
an agreeable penetrating odor. By the distillation 
of the liquid, an ethereal oily substance of great vola- 
tility is obtained, which excites a pricking sensation 
in the eyes, and a flow of tears, (Biichner.) 

The leaves of the tobacco plant present the same 
phenomena; when fresh they possess very little or 
no smell. When they are subjected to distillation 
Avith water, a weak ammoniacal liquid is obtained, 
upon which a fatty crystallizable substance swims, 
which does not contain nitrogen, and is quite desti- 
tute of smell. But when the same plant, after being 
dried, is moistened with water, tied together in small 
bundles, and placed in heaps, a peculiar process of 
decomposition takes place. Fermentation com- 
mences, and is accompanied by the absorption of 
oxygen ; the leaves now become warm and emit the 
characteristic smell of prepared tobacco and snufF. 
When the fermentation is carefully promoted and 
too high a heat avoided, this smell increases and be- 
comes more delicate; and after the fermentation is 
completed, an oily azotized volatile matter called 
nicotine is found in the leaves. This substance, 
— nicotine, which possesses all the properties of a 
base, was not present before the fermentation. The 
different kinds of tobacco are distinguished from one 
another, like wines, by having very different odori- 
ferous substances, which are generated along with 
the nicotine. 

We know, that most of the blossoms and vegetable 
substances which possess a smell owe this property 
to a volatile oil existing in them; but it is not less 
certain, that others emit a smell only when they 
undergo change or decomposition. 

Arsenic and arsenious acid are both quite inodor- 
ous. It is only during their oxidation that they emit 
their characteristic odor of garlic. The oil of the 
berries of the elder-tree, many kinds of oil of turpen- 



346 VINOUS FERMENTATION. 

tine, and oil of lemons, possess a smell only during 
their oxidation or decay. The same is the case with 
many blossoms; and Geiger has shown, that the 
smell of musk is owing to its gradual putrefaction 
and decay. 

It is also probable, that the peculiar odorous prin- 
ciple of many vegetable substances is newly formed 
during the fermentation of the saccharine juices of 
the plants. At all events, it is a fact, that very 
small quantities of the blossoms of the violet, elder, 
linden, or cowslip, added to a fermenting liquid, are 
sufficient to communicate a very strong taste and 
smell, which the addition of the water distilled from 
a quantity a hundred times greater would not effect. 
The various kinds of beer manufactured in Bavaria 
are distinguished by different flavors, which are 
given by allowing small quantities of the herbs and 
blossoms of particular plants to ferment along with 
the wort. On the Rhine, also, an artificial bouquet 
is often given to wine for fraudulent purposes, by the 
addition of several species of the sage and rue to 
the fermenting liquor ; but the fictitious perfume 
thus obtained differs from the genuine aroma, by its 
inferior durability, and by being gradually dissi- 
pated. 

The juice of grapes grown in different climates 
differs not only in the proportion of free acid which 
it contains, but also in respect to the quantity of 
sugar dissolved in it. The quantity of azotized 
matter in the juice seems to be the same in whatever 
parts the grapes may grow ; at least no difference 
has been observed in the amount of yeast formed 
during fermentation in the south of France, and on 
the Rhine. 

The grapes grown in hot climates, as well as the 
boiled juice obtained from them, are proportionally 
rich in sugar. Hence, during the fermentation of 
the juice, the complete decomposition of its azotized 
matters, and their separation in the insoluble state, 
are effected before all the sugar has been converted 



TAMOUS PROPERTIES OF WINES. 347 

into alcohol and carbonic acid. A certain quantity 
of the sugar consequently remains mixed with the 
wine in an undecomposed state, the condition neces- 
sary for its further decomposition being absent. 

The azotized matters in the juice of grapes of the 
temperate zones, on the contrary, are not completely 
separated in the insoluole state, when the entire 
transformation of the sugar is effected. The wine 
of these grapes, therefore, does not contain sugar, 
but variable quantities of undecomposed gluten in 
solution. 

This gluten gives the wine the property of becom- 
ing spontaneously converted into vinegar, when the 
access of air is not prevented. For it absorbs 
oxygen and becomes insoluble; and its oxidation is 
communicated to the alcohol, which is converted 
into acetic acid. 

By allowing the wine to remain at rest in casks 
with a very limited access of air, and at the lowest 
possible temperature, the oxidation of this azotized 
matter is effected without the alcohol undergoing 
the same change, a higher temperature being neces- 
sary to enable alcohol to combine with oxygen. As 
long as the wine in the stilling-casks deposites yeast, 
it can still be caused to ferment by the addition of 
sugar, but old well-layed wine has lost this property, 
because the condition necessary for fermentation, 
namely, a substance in the act of decomposition or 
putrefaction, is no longer present in it. 

In hotels and other places where wine is drawn 
gradually from a cask, and a proportional quantity 
of air necessarily introduced, its eremacausis, that 
is, its conversion into acetic acid, is prevented by 
the addition of a small quantity of sulphurous acid. 
This acid, by entering into combination with the 
oxygen of the air contained in the cask, or dissolved 
in the wine, prevents the oxidation of the organic 
matter. 

The various kinds of beer differ from one another 
in the same way as the wines. 



348 FERMENTATION OF BEER. 

English, French, and most of the German beers, 
are converted into vinegar when exposed to the 
action of air. JBut this property is not possessed by 
Bavarian beer, which may be kept in vessels only 
half-filled without acidifying or experiencing any 
change. This valuable quality is obtained for it by 
a peculiar management of the fermentation of the 
wort. The perfection of experimental knowledge 
has here led to the solution of one of the most beau- 
tiful problems of the theory of fermentation. 

Wort is proportionally richer in gluten than in 
sugar, so that during its fermentation in the common 
way, a great quantity of yeast is formed as a thick 
scum. The carbonic acid evolved during the process 
attaches itself to the particles of yeast, by which 
they become specifically lighter than the liquid in 
which they are formed, and rise to its surface. Glu- 
ten in the act of oxidation comes in contact with 
the particles of the decomposing sugar in the inte- 
rior of the liquid. The carbonic acid from the sugar 
and insoluble ferment from the gluten are disengaged 
simultaneously, and cohere together. 

A great quantity of gluten remains dissolved in 
the fermented liquid, even after the transformation 
of the sugar is completed, and this gluten causes 
the conversion of the alcohol into acetic acid, on 
account of its strong disposition to attract oxygen, 
and to undergo decay. Now, it is plain, that with 
its separation, and that of all substances capable of 
attracting oxygen, the beer would lose the property 
of becoming acid. This end is completely attained 
in the process of fermentation adopted in Bavaria. 

The wort, after having been treated with hops in 
the usual manner, is thrown into very wide flat 
vessels, in which a large surface of the liquid is 
exposed to the air. The fermentation is then allowed 
to proceed, while the temperature of the chambers 
in which the vessels are placed is never allowed to 
rise above from 45 to 50^ F. The fermentation lasts 
from three to six weeks, and the carbonic acid 



THE BAVARUN PROCESS. 349 

evolved during its continuance is not in large bub- 
bles which burst upon the surface of the liquid, but 
in small bubbles like those which escape from a 
liquid saturated by high pressure. The surface of 
the wort is scarcely covered with a scum, and all 
the yeast is deposited on the bottom of the vessel 
in the form of a viscous sediment. 

In order to obtain a clear conception of the great 
difference between the two kinds of fermentation, it 
may perhaps be sufficient to recall to mind the fact, 
that the transformation of gluten or other azotized 
matters is a process consisting of several stages. 
The first stage is the conversion of the gluten into 
insoluble ferment in the interior of the liquid, and 
as the transformation of the sugar goes on at the 
same time, carbonic acid and yeast are simultane- 
ously disengaged. It is known with certainty, that 
this formation of yeast depends upon oxygen being 
appropriated by the gluten in the act of decomposi- 
tion ; but it has not been sufficiently shown, whether 
this oxygen is derived from the water, sugar, or 
from the gluten itself; whether it combines directly 
with the gluten, or merely with its hydrogen, so as 
to form water. For the purpose of obtaining a 
definite idea of the process, we may designate the 
first chano;e as the staofe of oxidation. This oxida- 
tion of the gluten, then, and the transposition of the 
atoms of the sugar into alcohol and carbonic acid, 
are necessarily attendant on each other, so that if the 
one is arrested the other must also cease. 

Now, the yeast which rises to the surface of the 
liquid is not the product of a complete decomposi- 
tion, but is oxidized gluten, still capable of under- 
going a new transformation by the transposition of 
its constituent elements. By virtue of this condition 
it has the power to excite fermentation in a solution 
of sugar ; and if the gluten be also present, the 
decomposing sugar induces its conversion into fresh 
yeast, so that, in a certain sense, the yeast appears 
to reproduce itself. 

30 



350 FERMENTATION OF BEER. 

Yeast of this kind is oxidized gluten in a state of 
putrefaction, and by virtue of this state it induces 
a similar transformation in the elements of the sugar. 

The yeast formed during the fermentation of Ba- 
varian beer is oxidized gluten in a state of decay. 
The process of decomposition which its constituents 
are suffering, gives rise to a very protracted putre- 
faction {^fermentation) in the sugar. The intensity 
of the action is diminished in so great a degree, 
that the gluten which the fluid still holds in solution 
takes no part in it ; the sugar in fermentation does 
not excite a .similar state in the gluten. 

But the contact of the already decaying and pre- 
cipitated gluten or yeast, causes the eremacausis of 
the gluten dissolved in the \vort ; oxygen gas is 
absorbed from the air, and all the gluten in solution 
is deposited as yeast. 

The ordinary frothy yeast may be removed from 
fermenting beer by filtration, without the fermenta- 
tion being thereby arrested ; but precipitated yeast 
of Bavarian beer cannot be removed without the 
whole process of its fermentation being interrupted. 
The beer ceases to ferment altogether, or, if the 
temperature is raised, undergoes the ordinary fer- 
mentation. 

The precipitated yeast does not excite ordinary 
fermentation, and consequently is quite unfitted for 
the purpose of baking ; but the common frothy yeast 
can cause the kind of fermentation by which the 
former kind of yeast is produced. 

When common yeast is added to wort at a tem- 
perature of between 40^ and 45° F., a slow tranquil 
fermentation takes place, and a matter is deposited 
on the bottom of the vessel, which may be employed 
to excite new fermentation ; and when the same 
operation is repeated several times in succession, 
the ordinary fermentation changes into that process 
by which only precipitated yeast is formed. The 
yeast now deposited has lost the property of excit- 



THE BAVARIAN PROCESS. 351 

ing ordinary fermentation, but it produces the other 
process even at a temperature of 50° F. 

In wort subjected to fermentation, at a low tem- 
perature, with this kind of yeast, the condition 
necessary for the transformation of the sugar is the 
presence of that yeast; but for the conversion of 
gluten into ferment by a process of oxidation, some- 
thing more is required. 

When the power of gluten to attract oxygen is 
increased by contact with precipitated yeast in a 
state of decay, the unrestrained access of air is the 
only other condition necessary for its own conver- 
sion into the same state of decay, that is, for its 
oxidation. We have already seen, that the presence 
of free oxygen and gluten are conditions which 
determine the eremacausis of alcohol and its conver- 
sion into acetic acid, but they are incapable of exert- 
ing this influence at low temperatures. A low tem- 
perature retards the slow combustion of alcohol, 
while the gluten combines spontaneously with the 
oxygen of the air, just as sulphurous acid does when 
dissolved in water. Alcohol undergoes no such 
change at low temperatures, but during the oxidation 
of the gluten in contact with it, is placed in the same 
condition as the gluten itself when sulphurous acid 
is added to the wine in which it is contained. The 
oxygen of the air unites both with the gluten and 
alcohol of wine not treated with sulphurous acid ; 
but when this acid is present it combines with nei- 
ther of them, being altogether absorbed by the acid. 
The same thing happens in the peculiar process of 
fermentation adopted in Bavaria. The oxygen of 
the air unites only with the gluten and not with the 
alcohol, although it would have combined with both 
at higher temperatures, so as to form acetic acid. 

Thus, then, this remarkable process of fermenta- 
tion with the precipitation of a mucous-like ferment 
consists of a simultaneous putrefaction and decay in 
the same liquid. The sugar is in the state of putre- 
faction, and the gluten in that of decay. 



352 FERMENTATION OF BEER. 

Appert's method of preserving food, and this kind 
of fermentation of beer, depend on the same prin- 
ciple. 

In the fermentation of beer after this manner, all 
the substances capable of decay are separated from 
it by means of an unrestrained access of air, while 
the temperature is kept sufficiently low to prevent 
the alcohol from combining with oxygen. The re- 
moval of these substances diminishes the tendency 
of the beer to become acescent, or, in other words, 
to suffer a further transformation. 

In Appert's mode of preserving food, oxygen is 
allowed to enter into combination with the substance 
of the food, at a temperature at which decay, but 
neither putrefaction nor fermentation, can take place. 
With the subsequent exclusion of the oxygen and 
the completion of the decay, every cause which could 
effect further decomposition of the food is removed. 
The conditions for putrefaction are rendered insuffi- 
cient in both cases ; in the one by the removal of the 
substances susceptible of decay, in the other by the 
exclusion of the oxygen which would effect it. 

It has been stated to be uncertain, whether gluten 
during its conversion into common yeast, that is, 
into the insoluble state in which it separates from 
fermenting liquids, really combines directly with 
oxygen. If it does combine with oxygen, then the 
difference between gluten and ferment would be, 
that the latter would contain a larger proportion of 
oxygen. Now it is very difficult to ascertain this, 
and even their analyses cannot decide the question. 
Let us consider, for example, the relations of alloxan 
and alloxantin* to one another. Both of these bod- 
ies contain the same elements as gluten, although in 
different proportions. Now they are known to be 
convertible into each other, by oxygen being absorb- 
ed in the one case, and in the other extracted. Both 

* Products of the decomposition of uric acid by nitric acid, consisting 
of carbon, nitrogen, hydrogen, and oxygen. See description, &c. in 
Webster's Cliemistry, pp 425 and 430. 



FERMENTATION OF BEER. 353 

are composed of absolutely the same elements, in 
equal proportions ; with the single exception, that 
alloxantin contains 1 equivalent of hydrogen more 
than alloxan. 

When alloxantin is treated with chlorine and ni- 
tric acid, it is converted into alloxan, into a body, 
therefore, which is alloxantin minus 1 equivalent of 
hydrogen. If on the other hand a stream of sulphuret- 
ted hydrogen is conducted through alloxan, sulphur 
is precipitated, and alloxantin produced. It may be 
said, that in the first case hydrogen is abstracted, 
in the other added. But it would be quite as simple 
an explanation, if we considered them as oxides of 
the same radical : the alloxan being regarded as a 
combination of a body composed of C^ N^ H^ 0^ with 
2 equivalents of water, and alloxantin as a combina- 
tion of 3 atoms of water, with a compound consist- 
ino; of C^ W W 0^ The conversion of alloxan into 
alloxantin would in this case result from its eight 
atoms of oxygen being reduced to seven, while al- 
loxan would be formed out of alloxantin, by its com- 
bining with an additional atom of oxygen. 

Now, oxides are known which combine with water, 
and present the same phenomena as alloxan and al- 
loxantin. But no compounds of hydrogen are known 
which form hydrates ; and custom, which rejects all 
dissimilarity until the claim to peculiarity is quite 
proved, leads us to prefer an opinion, for which there 
is no further foundation than that of analogy. The 
woad (^Isatis tinctorid) and several species of the 
Neriwrn contain a substance similar in many respects 
to gluten, which is deposited as indigo blue, when 
an aqueous infusion of the dried leaves is exposed 
to the action of the air. Now it is very doubtful 
whether the blue insoluble indigo is an oxide of the 
colorless soluble indigo, or the latter a combination 
of hydrogen with the indigo blue. Dumas has found 
the same elements in both, except that the soluble 
compound contained 1 equivalent of hydrogen more 
than the blue. 

30* 



354 FERMENTATION OF BEER. 

In the same manner the soluble gluten may be con- 
sidered a compound of hydrogen, which becomes 
ferment by losing a certain quantity of this element 
when exposed to the action of the oxygen of the air 
under favorable circumstances. At all events, it is 
certain that oxygen is the cause of the insoluble con- 
dition of gluten ; for yeast is not deposited on keep- 
ing wine, or during the fermentation of Bavarian 
beer, unless oxygen has access to the fluid. 

Now, whatever be the form in which the oxygen 
unites with the gluten, — whether it combines di- 
rectly with it or extracts a portion of its hydrogen, 
forming water, — the products formed in the interior 
of the liquid, in consequence of the conversion of 
the gluten into ferment, will still be the same. Let 
us suppose that gluten is a compound of another 
substance with hydrogen, then this hydrogen must 
be removed during the ordinary fermentation of must 
and wort, by combining with oxygen, exactly as in 
the conversion of alcohol into aldehyde* by erema- 
causis. 

In both cases the atmosphere is excluded ; the 
oxygen cannot, then, be derived from the air, neither 
can it be supplied by the elements of w^ater, for it is 
impossible to suppose, that the oxygen will separate 
from the hydrogen of water, for the purpose of unit- 
ing with the hydrogen of gluten, in order again to 
form water. The oxygen, must, therefore, be ob- 
tained from the elements of sugar, a portion of which 
substance must, in order to the formation of ferment, 
undergo a different decomposition from that which 
produces alcohol. Hence a certain part of the sugar 
will not be converted into carbonic acid and alcohol, 
but will yield other products containing less oxygen 
than sugar itself contains. These products, as has 
already been mentioned, are the cause of the great 

* A liquid havinjr a peculiar ethereal smell, and obtained by passing 
the vapor of ether throuorh a large glass tube heated to redness, and by 
other processes. It consists of carbon 4 , hydrogen 4, oxygen 2. Its 
name is from the Latin, alcohol dehijdratus. 



THE BAVARIAN PROCESS. 355 

difference in the qualities of fermented liquids, and 
particularly in the quantity of alcohol which they 
contain. 

Must and wort do not, therefore, in ordinary fer- 
mentation, yield alcohol in proportion to the quantity 
of sugar which they hold in solution, a part of the 
sugar being employed in the conversion of gluten 
into ferment, and not in the formation of alcohol. 
But in the fermentation of Bavarian beer, all the 
sugar is expended in the production of alcohol ; and 
this is especially the case whenever the transforma- 
tion of the sugar is not accompanied by the forma- 
tion of yeast. 

It is quite certain, that in the distilleries of brandy 
from potatoes, where no yeast is formed, or only a 
quantity corresponding to the malt which has been 
added, the proportion of alcohol and carbonic acid 
obtained during the fermentation of the mash corre- 
sponds exactly to that of the carbon contained in 
the starch. It is also known, that the volume of car- 
bonic acid evolved during the fermentation of beet- 
roots gives no exact indication of the proportion of 
sugar contained in them, for less carbonic acid is 
obtained than the same quantity of pure sugar would 
yield. 

Beer obtained by the mode of fermentation adopt- 
ed in Bavaria contains more alcohol, and possesses 
more intoxicating properties, than that made by the 
ordinary method of fermentation, when the quanti- 
ties of malt used are the same. The strong taste 
of the former beer is generally ascribed to its con- 
taining carbonic acid in larger quantity, and in a 
state of more intimate combination ; but this opinion 
is erroneous. Both kinds of beer are, at the conclu- 
sion of the fermentation, completely saturated with 
carbonic acid, the one as much as the other. Like 
all other liquids, they both must retain such a por- 
tion of the carbonic acid evolved as corresponds to 
their power of solution, that is, to their volumes. 

The temperature of the fluid during fermentation 



356 FERMENTATION OF BEER. 

has a very important influence on the quantity of 
alcohol generated. It has been mentioned, that the 
juice of beet-roots allowed to ferment at from 86^ to 
95° (30^ to 35° C.) yields no alcohol; and that 
afterwards, in the place of the sugar, mannite, a 
substance incapable of fermentation, and containing 
very little oxygen, is found, together with lactic acid 
and mucilage. The formation of these products di- 
minishes in proportion as the temperature is lower. 
But in vegetable juices, containing nitrogen, it is 
impossible to fix a limit, where the transformation 
of the sugar is undisturbed by any other process of 
decomposition. 

It is known, that in the fermentation of Bavarian 
beer, the action of the oxygen of the air, and the 
low temperature, cause complete transformation of 
the sugar into alcohol ; the cause which would pre- 
vent that result, namely, the extraction of the oxy- 
gen of part of the sugar by the gluten, in its con- 
version into ferment, being avoided by the introduc- 
tion of oxygen from without. 

The quantity of matters in the act of transforma- 
tion is naturally greatest at the beginning of the 
fermentation of must and wort ; and all the phenom- 
ena which accompany the process, such as evolution 
of gas, and heat, are best observed at that time. 
These signs of the changes proceeding in the fluid 
diminish when the greater part of the sugar has 
undergone decomposition ; but they must cease en- 
tirely before the process can be regarded as com- 
pleted. 

The less rapid process of decomposition which 
succeeds the violent evolution of gas, continues in 
wine and beer until the sugar has completely dis- 
appeared; and hence it is observed, that the specific 
gravity of the liquid diminishes during many months. 
This slow fermentation, in most cases, resembles the 
fermentation of Bavarian beer, the transformation 
of the dissolved sugar being in part the result of a 
slow and continued decomposition of the precipita- 



DECAY OF WOODY FIBRE. 357 

ted yeast ; but a complete separation of the azotized 
substances dissolved in it cannot take place when 
air is excluded.* 

Neither alcohol alone, nor hops, nor indeed both 
together, preserve beer from becoming acid. The 
better kinds of ale and porter in England are pro- 
tected from acidity, but at the loss of the interest 
of an immense capital. They are placed in large 
closed wooden vessels, the surfaces of which are 
covered with sand. In these they are allowed to lie 
for several years, so that they are treated in a man- 
ner exactly similar to wine during its ripening. 

A gentle diffusion of air takes place through the 
pores of the wood, but the quantity of azotized sub- 
stances being very great in proportion to the oxygen 
which enters, they consume it, and prevent its union 
with the alcohol. But the beer treated in this way 
does not keep for two months without acidifying if 
it be placed in smaller vessels, to which free access 
of the air is permitted. 



CHAPTER X. 

DECAY OF WOODY FIBRE. 

The conversion of woody fibre into the substances 
termed humus and mould is, on account of its in- 
fluence on vegetation, one of the most remarkable 
processes of decomposition which occur in nature. 

Decay is not less important in another point of 

* The great influence which a rational management of fermentalion 
exercises upon the quality of beer is well known in several of the Ger- 
man states. In the grand-duchy of Hesse, for example, a considerable 
premium is offered for the preparation of beer, according to the 
Bavarian method ; and the premium is to be adjudged to any one who 
can prove, that the beer brewed by him has lain for six months in the 
store-vats without becoming acid. Hundreds of casks of beer became 
changed to vinegar before an empirical knowledge of those conditions 
was obtained, the influence of which is rendered intelligible by the 
theory. — L. 



358 DECAY OF WOODY FIBRE. 

view; for, by means of its influence on dead vege- 
table matter, the oxygen which plants retained dur- 
ing life is again restored to the atmosphere. 

The decomposition of woody fibre is effected in 
three forms, the results of which are different, so 
that it is necessary to consider each separately. 

The first takes place when it is in the moist con- 
dition, and subject to free uninterrupted access of 
air ; the second occurs when the air is excluded ; 
and the third when the wood is covered with water, 
and in contact with putrefying organic matter. 

It is known that woody fibre may be kept under 
water, or in dry air, for thousands of years without 
suffering any appreciable change ; but that w^hen 
brought into contact wuth air, in the moist con- 
dition it converts the oxygen surrounding it into the 
same volume of carbonic acid, and is itself gradually 
changed into a yellowish brown, or black matter, of 
a loose texture.* 

It has already been mentioned, that pure woody 
fibre contains carbon and the elements of water. 
Humus, however, is not produced by the decay of 
pure woody fibre, but by that of wood which contains 
foreign soluble and insoluble organic substances, be- 
sides its essential constituents. 

The relative proportions of the component elements 
are, on this account, different in oak wood and in 
beech, and the composition of both of these differs 
very much from woody fibre, w^hich is the same in 
all vegetables. The difference, however, is so triv- 
ial, that it may be altogether neglected in the con- 
sideration of the questions which will now be brought 
under discussion; besides, the quantity of the for- 
eign substances is not constant, but varies according 
to the season of the year. 

* According to the experiments of De Saussure, 240 parts of dry 
saw-dust of oak wood convert 10 cubic inches of oxygen into the same 
quantity of carbonic acid, which contains 3 parts, by weight, of car- 
bon ; while the weight of the sawdust is diminished by 15 parts. 
Hence, 12 parts, by weight, of water, are at the same time separated 
from the elements of the wood. — L. 



DECAY OF WOODY FIBRE. 359 

Accoi'ding to the careful analysis of Gay-Lussac 
and Thenai'd, 100 parts of oak wood, dried at 212^ 
(100° C), from which all soluble substances had 
been extracted by means of water and alcohol, con- 
tained 52-53 parts of carbon, and 47-47 parts of hy- 
drogen and oxygen, in the same proportion as they 
are contained in water. 

Now it has been mentioned, that moist wood acts 
in oxygen gas exactly as if its carbon combined di- 
rectly with oxygen, and that the products of this 
action are carbonic acid and humus. 

If the action of the oxygen were confined to the 
carbon of the wood, and if nothings but carbon were 
removed from it, the remaining elements would ne- 
cessarily be found in the humus, unchanged except 
in the particular of being combined with less carbon. 
The final result of the action would therefore be a 
complete disappearance of the carbon, w^hilst noth- 
ing but the elements of water would remain. 

But when decaying wood is subjected to exami- 
nation in different stages of its decay, the remark- 
able result is obtained, that the proportion of carbon 
in the different products augments. Consequently, 
if we did not take into consideration the evolution 
of carbonic acid under the influence of the air, the 
conversion of wood into humus might be viewed as 
a removal of the elements of water from the carbon. 

The analysis of mouldered oak wood, which was 
taken from the interior of the trunk of an oak, and 
possessed a chocolate brown color and the structure 
of wood, showed that 100 parts of it contained 53-56 
parts of carbon and 46-44 parts of hydrogen and 
oxygen in the same relative proportions as in w^ater. 
From an examination of mouldered w^ood of a light- 
brown color, easily reducible to a fine powder, and 
taken from another oak, it appeared that it contained 
56-211 carbon and 43-789 water. 

These indisputable facts point out the similarity 
of the decay of wood, with the slow combustion or 
oxidation of bodies which contain a large quantity 



360 DECAY OF WOODY FIBRE. 

of hydrogen. Viewed as a kind of combustion, it 
would indeed be a very extraordinary process, if the 
carbon combined directly with the oxygen; for it 
would be a combustion in which the carbon of the 
burning body augmented constantly, instead of 
diminishing. Hence it is evident, that it is the hy- 
drogen which is oxidized at the expense of the 
oxygen of the air; while the carbonic acid is formed 
from the elements of the wood. Carbon never com- 
bines at common temperatures with oxygen, so as to 
form carbonic acid. 

In whatever stage of decay wood may be, its ele- 
ments must always be capable of being represented 
by their equivalent numbers. 

The following formula illustrates this fact with 
great clearness : 

Co6 H22 022 — oak wood, according to Gay-Lussac and Thenard.* 
C35 H20 O 20 — humus from oak wood (Meyer). f 
C34H18 01d~ " » (Dr. Will) 4 

It is evident from these numbers, that for every 
two equivalents of hydrogen which are oxidized, 
two atoms of oxygen and one of carbon are set 
free. 

Under ordinary circumstances, woody fibre requires 
a very long time for its decay; but this process is 
of course much accelerated by an elevated tempera- 
ture and free unrestrained access of air. The decay, 
on the contrary, is much retarded by absence of 
moisture, and by the wood being surrounded with 
an atmosphere of carbonic acid, which prevents the 
access of air to the decaying matters. 

Sulphurous acid, and all antiseptic substances, 
arrest the decay of woody fibre. It is well known, 
that corrosive sublimate is employed for the purpose 
of protecting the timber of ships from decay; it is 
a substance which completely deprives vegetable or 
animal matters, the most prone to decomposition, of 

* The calculation gives 52-5 carbon, and 475 water, 
t The calculation gives 54 carbon, and 46 water. 
t The calculation gives 5G carbon, and 44 water. 



WOODY FIBRE. 361 

their property of entering into fermentation, putre- 
faction, or decay.* 

But the decay of woody fibre is very much accel- 
erated by contact with alkalies or alkaline earths ; 
for these enable substances to absorb oxygen, which 
do not possess this power themselves; alcohol, 
gallic acid, tannin, the vegetable coloring matters, 
and several other substances, are thus affected by 
them. Acids produce quite an opposite effect ; they 
greatly retard decay. 

Heavy soils, consisting of loam, retain longest the 
most important condition for the decay of the vege- 
table matter contained in them, viz., "water; but 
their impermeable nature prevents contact with the 
air. 

In moist sandy soils, particularly such as are com- 
posed of a mixture of sand and carbonate of lime, 
decay proceeds very quickly, it being aided by the 
presence of the slightly alkaline lime. 

Now let us consider the decay of woody fibre 
during a very long period of time, and suppose that 
its cause is the gradual removal of the hydrogen in 
the form of water, and the separation of its oxygen 
in that of carbonic acid. It is evident, that if we 
subtract from the formula C^% H", 0", the 22 equiv- 
alents of oxygen, with 11 equivalents of carbon, and 
22 equivalents of hydrogen, which are supposed to 
be oxidized by the oxygen of the air, and separated 
in the form of water; then from 1 atom of oak wood, 
25 atoms of pure carbon will remain as the final 
product of the decay. In other words, 100 parts of 
oak, W'hich contain 52*5 parts of carbon, will leave 
as a residue 37 parts of carbon, which must remain 
unchanged, since carbon does not combine with 
oxygen at common temperatures. 

But this final result is never attained in the decay 
of wood under common circumstances ; and for this 
reason, that with the increase of the proportion of 

* See an account of the process for " kyanizing" timber in tlie Farm- 
er's Register, Vol. III. p. 368. 

31 



362 DECAY OF WOODY FIBRE. 

carbon in the residual humus, as in all decomposi- 
tions of this kind, its attraction for the hydrogen, 
which still remains in combination, also increases, 
until at length the affinity of oxygen for the hydro- 
gen is equalled by that of the carbon for the same 
element. 

In proportion as the decay of woody fibre ad- 
vances, its property of burning with flame, or in 
other words, of developing carburetted hydrogen on 
the application of heat, diminishes. Decayed wood 
burns without flame ; whence no other conclusion 
can be drawn, than that the hydrogen, which analysis 
shows to be present, is not contained in it in the 
same form as in wood. 

Decayed oak contains more carbon than fresh 
wood, but its hydrogen and oxygen are in the same 
proportion. 

We should naturally expect that the flame given 
out by decayed wood would be more brilliant, in 
proportion to the increase of its carbon; but we find, 
on the contrary, that it burns like tinder, exactly as if 
no hydrogen were present. For the purposes of fuel, 
decayed or diseased wood is of little value, for it 
does not possess the property of burning with flame, 
a property upon which the advantages of common 
wood depend. The hydrogen of decayed wood must 
consequently be supposed to be in the state of water; 
for had it any other form, the characters we have de- 
scribed would not be possessed by the decayed wood. 

If we suppose decay to proceed in a liquid, w^hich 
contains both carbon and hydrogen, then a compound 
containing still more carbon must be formed, in a 
manner similar to the production of the crystalline 
colorless naphthalin from a gaseous compound of 
carbon and hydrogen. And if the compound thus 
formed were itself to undergo further decay, the 
final result must be the separation of carbon in a 
crystalline form. 

Science can point to no process capable of ac- 
counting for the origin and formation of diamonds, 



VEGETABLE MOULD. 363 

except the process of decay. Diamonds cannot be 
produced by the action of fire, for a high temperature 
and the presence of oxygen gas, would call into 
play their combustibility. But there is the greatest 
reason to believe that they are formed in the humid 
way, that is, in a liquid, and the process of decay is 
the only cause to which their formation can with 
probability be ascribed. 

Amber, fossil resin, and the acids in mellite, are 
the products of vegetable matter which has suffered 
decomposition. They are found in wood or brown 
coal, and have evidently proceeded from the decom- 
position of substances which were contained in quite 
a different form in the living plants. They are all 
distinguished by the proportionally small quantity 
of hydrogen which they contain. The acid from 
mellite (mellitic acid) contains precisely the same 
proportions of carbon and oxygen as that from 
amber (succinic acid); they differ only in the pro- 
portion of their hydrogen. M. Bromeis* found, that 
succinic acid might be artificially formed by the 
action of nitric acid on stearic acid, a true process 
of eremacausis ; the experiment was made in this 
laboratory (Giessen). 



CHAPTER XI. 

VEGETABLE MOULD. 

The term vegetable mould, in its general significa- 
tion, is applied to a mixture of disintegrated miner- 
als, with the remains of animal and vegetable sub- 
stances. It may be considered as earth in which 
humus is contained in a state of decomposition. Its 
action upon the air has been fully investigated by 
Ingenhouss and De Saussure. 

When moist vegetable mould is placed in a vessel 

* Liebig's Annalen, Band xxxiv., heft 3. 



364 VEGETABLE MOULD. 

full of air, it extracts the oxygen therefrom with 
greater rapidity than decayed wood, and replaces it 
by an equal volume of carbonic acid. When this 
carbonic acid is removed and fresh air admitted, 
the same action is repeated. 

Cold water dissolves only loiooth of its own weight 
of vegetable mould ; and the residue left on its 
evaporation consists of common salt with traces of 
sulphate of potash and lime, and a minute quantity 
of organic matter, for it is blackened when heated 
to redness. Boiling water extracts several sub- 
stances from vegetable mould, and acquires a yellow 
or yellowish brown color, which is dissipated by 
absorption of oxygen from the air, a black flocculent 
deposit being formed. When the colored solution is 
evaporated, a residue is left which becomes black on 
being heated to redness, and afterwards yields car- 
bonate of potash when treated with water. 

A solution of caustic potash becomes black when 
placed in contact with vegetable mould, and the ad- 
dition of acetic acid to the colored solution causes no 
precipitate or turbidness. But dilute sulphuric acid 
throws down a light flocculent precipitate of a brown 
or black color, from which the acid can be removed 
with difficulty by means of water. When this pre- 
cipitate, after having been washed with water, is 
brouo-ht whilst still moist under a receiver filled with 
oxygen, the gas is absorbed with great rapidity; and 
the same thing takes place when the precipitate is 
dried in the air. In the perfectly dry state it has 
entirely lost its solubility in water, and even alkalies 
dissolve only traces of it. 

It is evident, therefore, that boiling water extracts 
a matter from vegetable mould, which owes its solu- 
bility to the presence of the alkaline salts contained 
in the remains of plants. This substance is a pro- 
duct of the incomplete decay of woody fibre. Its 
composition is intermediate between woody fibre and 
humus, into which it is converted, by being exposed 
in a moist condition to the action of the air. 



DECOMPOSITION OF WOOD, COAL, ETC. 365 



CHAPTER XII. 

ON THE MOULDERING OF BODIES. — PAPER, BROWN 
COAL, AND MINERAL' COAL. 

The decomposition of wood, woody fibre, and all 
vegetable bodies when subjected to the action of 
water, and excluded from the air, is termed mould- 
ering. 

Wood, or brown coal and mineral coal, are the re- 
mains of vegetables of a former world ; their ap- 
pearance and characters show, that they are products 
of the processes of decomposition termed decay and 
putrefaction. We can easily ascertain by analysis 
the manner in which their constituents have been 
changed, if we suppose the greater part of their bulk 
to have been formed from woody fibre. 

But it is necessary, before we can obtain a distinct 
idea of the manner in which coal is formed, to con- 
sider a peculiar change which woody fibre suffers by 
means of moisture, when partially or entirely ex- 
cluded from the air. 

It is known, that when pure woody fibre, as linen, 
for example, is placed in contact with water, con- 
siderable heat is evolved, and the substance is 
converted into a soft friable mass, which has lost 
all coherence. This substance was employed in the 
fabrication of paper before the use of chlorine, as an 
agent for bleaching. The rags employed for this 
purpose were placed in heaps, and it was observed, 
that on their becoming warm a gas was disengaged, 
and their weight diminished from 18 to 25 per cent. 

When sawdust moistened with water is placed in 
a closed vessel, carbonic acid gas is evolved in the 
same manner as when air is admitted. A true putre- 
faction takes place, the wood assumes a white color, 
loses its peculiar texture, and is converted into a 
rotten friable matter. 
31* 



366 DECOMPOSITION OF WOOD, COAL, ETC. 

The white decayed wood found in the interiors of 
trunks of dead trees which have been in contact with 
water, is produced in the way just mentioned. 

An analysis of wood of this kind, obtained from 
the interior of the trunk of an oak, yielded, after 
having been dried at 212°, 

Carbon 48-11 . . . 48-14 

Hydrogen (v31 . . 606 

Oxygen 4531 . . . 44-43 

Ashes 127 . . 1-37 



100-00 10000 

Now, on comparing the proportions obtained from 
these numbers with the composition of oak wood, ac- 
cording to the analysis of Gay-Lussac and Thenard, 
it is immediately perceived, ihat a certain quantity 
of carbon has been separated from the constituents 
of wood, whilst the hydrogen is, on the contrary, in- 
creased. The numbers obtained by the analysis cor- 
respond very nearly to the formula C33 H27 024.* 

The elements of water have, therefore, become 
united with the wood, whilst carbonic acid is disen- 
gaged by the absorption of a certain quantity of 
oxygen. 

If the elements of 5 atoms of water and 3 atoms 
of oxygen be added to the composition of the woody 
iibre of the oak, and 3 atoms of carbonic acid de- 
ducted, the exact formula for white mouldered wood 
is obtained. 

Wood C36H22 022 

To this add 5 atoms of water . . H 5 O 5 

3 atoms of oxygen ... 03 

C36 H27 O 30 
Subtract from this 3 atoms carbonic acid C 3 O 6 



C33 H27 024 

The process of mouldering is, therefore, one of 
putrefaction and decay, proceeding simultaneously, 
in which the oxygen of the air and the component 



* The calculation from this formula gives in 100 parts 47-9 carbon, 
61 hydrogen, and 46 oxygen. 



DECOMPOSITION OF WOOD, COAL, ETC. 367 

parts of water take part. But the composition of 
mouldered wood must change according as the 
access of oxygen is more or less prevented. White 
mouldered beech-wood yielded on analysis 47*67 
carbon, 5-67 hydrogen, and 46'6S oxygen ; this cor- 
responds to the formula C33 H25 024. 

The decomposition of wood assumes, therefore, 
two different forms, according as the access of the 
air is free or restrained. In both cases carbonic 
acid is generated ; and in the latter case, a certain 
quantity of water enters into chemical combination. 

It is highly probable, that in this putrefactive 
process, as well as in all others, the oxygen of the 
water assists in the formation of the carbonic acid. 

Wood coal (brown coal of Werner) must have 
been produced by a process of decomposition similar 
to that of mouldering. But it is not easy to obtain 
wood coal suited for analysis, for it is generally 
impregnated with resinous or earthy substances, by 
which the composition of those parts which have 
been formed from woody fibre is essentially changed. 

The wood coal, which forms extensive layers in 

the Wetterau (a district in Hesse Darmstadt), is 

distinguished from that found in other places, by 

possessing the structure of wood unchanged, and by 

containing no bituminous matter. This coal was 

subjected to analysis, a piece being selected upon 

which the annual circles could be counted. It was 

obtained from the vicinity of Laubach; 100 parts 

contained 

Carbon . . . 57-28 

Hydrogen . . . 6"03 

Oxygen . . . 36-10 

Ashes .... 0-59 



100-00 



The large amount of carbon, and small quantity 
of oxygen, constitute the most obvious difference 
between this analysis and that of wood. It is evi- 
dent, that the wood which has undergone the change 
into coal must have parted with a certain portion of 



368 DECOMPOSITION OF WOOD, COAL, ETC. 

its oxygen. The proportion of these numbers is 

expressed by the formula C33 H21 016.* 

When these numbers are compared with those 

obtained by the analysis of oak, it would appear 

that the brown coal was produced from woody fibre 

by the separation of one equivalent of hydrogen, 

and the elements of three equivalents of carbonic 

acid. 

1 atom wood C36 H22 022 

Minus 1 atom hydrogen and 3 atoms car- ? n o u i /^ <? 
bonic acid : ^. . . . ^ C 3 H 1 O 6 



Wood Coal . . C33 H21 016 

All varieties of wood coal, from whatever strata 
they may be taken, contain more hydrogen than 
wood does, and less oxygen than is necessary to 
form water with this hydrogen; consequently, they 
must all be produced by the same process of decom- 
position. The excess of hydrogen is either hydro- 
gen of the wood which has remained in it unchanged, 
or it is derived from some exterior source. The 
analysis of wood coal from Ringkuhl, near Cassel, 
where it is seldom found in pieces with the structure 
of wood, gave, when dried at 212^, 



Carbon 


62 60 


6383 


Hydrogen 


5 02 


. 4-80 


Oxygen 


26-52 


25-51 


Ashes 


5-86 


. 5-86 



100-00 10000 

The proportions derived from these numbers cor- 
respond very closely to the formula C^^ H'* 0% or 
they represent the constituents of wood, from which 
the elements of carbonic acid, water, and 2 equiva- 
lents hydrogen, have been separated. 

C36H22 0-22=Wood. 
Subtract C 4 H 7 Ol3=:4 atoms carbonic acid -f-5 atoms of water 
-\-2 atoms of hydrogen. 

C32 H15 O 9= Wood coal from Ringkuhl. 
The formation of both these specimens of wood 

* The calculation give.=i 57 5 carbon, and 5-98 hydrogen. 



FORMATION OF WOOD COAL. 369 

coal appears from these formulae to have taken place 
under circumstances vvhich did not entirely exclude 
the action of the air, and consequent oxidation and 
removal of a certain quantity of hydrogen. Now 
the Laubacher coal is covered with a layer of basalt, 
and the coal of Ringkuhl was taken from the lowest 
seam of layers, which possess a thickness of from 
90 to 120 feet; so that both may be considered as 
well protected from the air. 

During the formation of brown coal, the elements 
of carbonic acid have been separated from the wood 
either alone, or at the same time with a certain quan- 
tity of water. It is quite possible, that the difference 
in the process of decomposition may depend upon 
the high temperature and pressure under which the 
decomposition took place. At least, a piece of wood 
assumed the character and appearance of Laubacher 
coal, after being kept for several weeks in the boiler 
of a steam-engine, and had then precisely the same 
composition. The change in this case was effected in 
water, at a temperature of from 334° to 352° F. 
(150°- 160° C), and under a corresponding pres- 
sure. The ashes of the wood amounted to 0*51 per 
cent. ; a little less, therefore, than those of the Lau- 
bacher coal ; but this must be ascribed to the pecu- 
liar circumstances under which it was formed. The 
ashes of plants examined by Berthier amounted 
always to much more than this. 

The peculiar process by which the decomposition 
of these extinct vegetables has been effected, namely, 
a disengagement of carbonic acid from their sub- 
stance, appears still to go on at great depths in all 
the layers of wood coal. At all events it is remark- 
able, that springs impregnated with carbonic acid 
occur in many places, in the country between Meiss- 
ner, in the electorate of Hesse, and the Eifel, which 
are known to possess large layers of wood coal. 
These springs of mineral water are produced on the 
spot at which they are found ; the springs of com- 



370 CONVERSION OF WOOD 

raon water meeting with carbonic acid during their 
ascent, and becoming impregnated with it. 

In the vicinity of the layers of wood coal at Salz- 
hausen (Hesse Darmstadt) an excellent acidulous 
spring of this kind existed a few years ago, and 
supplied all the inhabitants of that district; but it 
was considered advantageous to surround the sides 
of the spring with sandstone, and the consequence 
was, that all the outlets to the carbonic acid were 
closed, for this gas generally gains access to the 
water from the sides of the spring. From that time 
to the present this valuable mineral water has dis- 
appeared, and in its place is found a spring of com- 
mon water. 

Springs of water impregnated with carbonic acid 
occur at Schwalheim, at a very short distance from 
the layers of wood coal at Dorheim. M. Wilhelmi 
observed some time since, that they are formed of 
common spring water which ascends from below, and 
of carbonic acid which issues from the sides of the 
spring. The same fact has been shown to be the 
case in the famed Fachinger spring, by M. Schapper. 

The carbonic acid gas from the springs in the 
Eifel, is, according to BischofF, seldom mixed with 
nitrogen or oxygen, and is probably produced in a 
manner similar to that just described. At any rate 
the air does not appear to take any part in the for- 
mation of these acidulous springs. Their carbonic 
acid has evidently not been formed either by a com- 
bustion at high or low temperatures; for if it were 
so, the gas resulting from the combustion would ne- 
cessarily be mixed with | of nitrogen, but it does 
not contain a trace of this element. The bubbles of 
gas which escape from these springs are absorbed 
by caustic potash, with the exception of a residuum 
too small to be appreciated. 

The wood coal of Dorheim and Salzhausen must 
have been formed in the same way as that of the 
neighboring village of Laubach ; and since the latter 
contains the exact elements of woody fibre, minus a 



INTO BROWN OR WOOD COAL. 371 

certain quantity of carbonic acid, its composition 
indicates very plainly the manner in which it has 
been produced. 

The coal of the upper bed is subjected to an in- 
cessant decay by the action of the air, by means of 
which its hydrogen is removed in the same manner 
as in the decay of wood. This is recognised by the 
way in which it burns, and by the formation of car- 
bonic acid in the mines. 

The gases which are formed in mines of wood coal, 
and cause danger in their working, are not combus- 
tible or inflammable as in mines of mineral coal ; 
but they consist generally of carbonic acid gas, and 
are very seldom intermixed with combustible gases. 

Wood coal from the middle bed of the strata at 
Ringkuhl gave on analysis 65*40, — 64*01 carbon and 
4*75, — 4*76* hydrogen; the proportion of carbon 
here is the same as in specimens procured from 
greater depths, but that of the hydrogen is much 
less. 

Wood and mineral coal are always accompanied 
by iron pyrites (sulphuret of iron) or zinc blende 
(sulphuret of zinc); which minerals are still formed 
from salts of sulphuric acid, with iron or zinc, during 
the putrefaction of all vegetable matter. It is pos- 
sible, that the oxygen of the sulphates in the layers 
of wood coal is the means by which the removal of 
the hydrogen is effected, since wood coal contains 
less of this element than wood. 

According to the analysis of Richardson and Reg- 
nault, the composition of the combustible materials 
in splint coal from Newcastle, and cannel coal from 
Lancashire, is expressed by the formula C24 H13 0. 
When this is compared with the composition of 
woody fibre, it appears that these coals are formed 
from its elements, by the removal of a certain quan- 
tity of carburetted hydrogen and carbonic acid in 

* The analysis of brown coal from Ringkuhl, as well as all those of 
the same substance oriven in this work, have been executed in this labo- 
ratory by M. Kiihnert of Cassel. — L. 



372 CONVERSION OF WOOD INTO MINERAL COAL. 

the form of combustible oils. The composition of 
both of these coals is obtained by the subtraction 
of 3 atoms of carburetted hydrogen, 3 atoms of 
water, and 9 atoms of carbonic acid from the formula 

of wood. 

I C36H22 022 = wood 
3 atoms of carburetted hydrogen C 3 HC | 
3 atoms of water . . H 3 03 I 

9 atoms of carbonic acid . C 9 018 C12 H9 021 



Mineral coal | C24 H13 O 

Carburetted hydrogen generally accompanies all 
mineral coal; other varieties of coal contain volatile 
oils, which may be separated by distillation with 
water. (Reichenbach.) The origin of naphtha is 
owing to a similar process of decomposition. Caking 
coal from Caresfield, near Newcastle, contains the 
elements of cannel coal, minus the constituents of 
olefiant gas C4 H4. 

The inflammable gases which stream out of clefts 
in the strata of mineral coal, or in rocks of the coal 
formations, always contain carbonic acid, according 
to a recent examination by BischofF, and also car- 
buretted hydrogen, nitrogen, and olefiant gas ; the 
last of which had not been observed, until its ex- 
istence in these gases was pointed out by Bischoff. 
The analysis of fire-damp, after it had been treated 
with caustic potash, showed its constituents to be. 

Gas from an 
abandoned 
mine near 
Wallesweiler. 
Vol. 
Light carburetted hydrogen 91 3G 
Olefiant gas . . 632 

Nitrogen gas . . 2- 32 



Gerhard's 


pas- 


Gas from a 


sage near 


Lu- 


mine near 


isenthal. 




Liekwege. 


Vol. 




Vol. 


8308 




79' 10 


1-98 




1611 


14 94 




4-79 



10000 lOOOO 10000 

The evolution of these gases proves, that changes 
are constantly proceeding in the coal. 

It is obvious from this, that a continual removal 
of oxygen in the form of carbonic acid is effected 
from layers of wood coal, in consequence of which 
the wood must approach gradually to the composition 



POISONS, CONTAGIONS, MIASMS. 373 

of mineral coal. Hydrogen, on the contrary, is dis- 
engaged from the constituents of mineral coal in the 
form of a compound of carbo-hydrogen ; a complete 
removal of all the hydrogen would convert coal into 
anthracite. 

The formula C36 H22 022, which is given for 
wood, has been chosen as the empirical expression 
of the analysis, for the purpose of bringing all the 
transformations, which woody fibre is capable of 
undergoing, under one common point of view. 

Now, although the correctness of this formula 
must be doubted, until we know with certainty the 
true constitution of woody fibre, this cannot have 
the smallest influence on the account given of the 
changes to which woody fibre must necessarily be 
subjected in order to be converted into wood or 
mineral coal. The theoretical expression refers to 
the quantity, the empirical merely to the relative pro- 
portion in which the elements of a body are united. 
Whatever form the first may assume, the empirical 
expression must always remain unchanged. 



CHAPTER XHI. 

ON POISONS, CONTAGIONS, AND MIASMS. 

A GREAT many chemical compounds, some derived 
from inorganic nature, and others formed in animals 
and plants, produce peculiar changes or diseases in 
the living animal organism. They destroy the vital 
functions of individual organs ; and when their ac- 
tion attains a certain degree of intensity, death is 
the consequence. 

The action of inorganic compounds, such as acids, 
alkalies, metallic oxides, and salts, can in most cases 
be easily explained. They either destroy the con- 
tinuity of particular organs, or they enter into com- 
32 



374 POISONS, CONTAGIONS, MIASMS. 

bination with their substance. The action of sul- 
phuric, muriatic, and oxalic acids, hydrate of potash, 
and all those substances which produce the direct 
destruction of the organs with which they come 
into contact, may be compared to a piece of iron, 
which can cause death by inflicting an injury on par- 
ticular organs, either when heated to redness, or 
when in the form of a sharp knife. Such substances 
are not poisons in the limited sense of the word, for 
their injurious action depends merely upon their 
condition. 

The action of the proper inorganic poisons is 
owing, in most cases, to the formation of a chemical 
compound by the union of the poison with the con- 
stituents of the organ upon which it acts ; it is 
owing to an exercise of a chemical affinity more 
powerful than the vitality of the organ. 

It is well to consider the action of inorganic sub- 
stances in general, in order to obtain a clear con- 
ception of the mode of action of those which are 
poisonous. We find that certain soluble compounds, 
when presented to different parts of the body, are 
absorbed by the blood, whence they are again elim- 
inated by the organs of secretion, either in a changed 
or in an unchanged state. 

Iodide of potassium, sulpho-cyanuret of potassium, 
ferro-cyanuret of potassium, chlorate of potash, sili- 
cate of potash, and all salts with alkaline bases, 
when administered internally to man and animals in 
dilute solutions, or applied externally, may be again 
detected in the blood, sweat, chyle, gall, and splenic 
veins ; but all of them are finally excreted from the 
body through the urinary passages. 

Each of these substances, in its transit, produces 
a peculiar disturbance in the organism, — in other 
words, they exercise a medicinal action upon it, but 
they themselves suffer no decomposition. If any of 
these substances enter into combination with any 
part of the body, the union cannot be of a perma- 
nent kind ; for their reappearance in the urine shows 



\ 



EFFECTS OF SALTS ON THE ORGANISM. 375 

that any compounds thus formed must have been 
again decomposed by the vital processes. 

Neutral citrates, acetates, and tartrates of the 
alkalies, suffer change in their passage through the 
organism. Their bases can indeed be detected in 
the urine, but the acids have entirely disappeared, 
and are replaced by carbonic acid which has united 
with the bases. (Gilbert Blane and Wohler.) 

The conversion of these salts of organic acids 
into carbonates, indicates that a considerable quan- 
tity of oxygen must have united with their elements. 
In order to convert 1 equivalent of acetate of potash 
into the carbonate of the same base, 8 equivalents 
of oxygen must combine with it, of which either 2 
or 4 equivalents (according as an acid or neutral 
salt is produced) remain in combination with the 
alkali; whilst the remaining 6 or 4 equivalents are 
diseno:ao:ed as free carbonic acid. There is no evi- 
dence presented by the organism itself, to which 
these salts have been administered, that any of its 
proper constituents have yielded so great a quantity 
of oxygen as is necessary for their conversion into 
carbonates. Their oxidation can, therefore, only be 
ascribed to the oxygen of the air. 

During the passage of these salts through the 
lungs, their acids take part in the peculiar process 
of eremacausis which proceeds in that organ; a cer- 
tain quantity of the oxygen gas inspired unites with 
their constituents, and converts their hydrogen into 
water, and their carbon into carbonic acid. Part of 
this latter product (1 or 2 equivalents) remains in 
combination wath the alkaline base, forming a salt 
which suffers no further change by the process of 
oxidation; and it is this salt which is separated by 
the kidneys or liver. 

It is manifest, that the presence of these organic 
salts in the blood must produce a change in the pro- 
cess of respiration. A part of the oxygen inspired, 
which usually combines with the constituents of the 
blood, must, when they are present, combine with 



376 POISONS, CONTAGIONS, MIASMS. 

their acids, and thus be prevented from performing 
its usual office. The immediate consequence of this 
must be the formation of arterial blood in less quan- 
tity, or in other words, the process of respiration 
must be retarded. 

Neutral acetates, tartrates, and citrates placed in 
contact with the air, and at the same time with 
animal or vegetable bodies in a state of eremacausis, 
produce exactly the same effects as we have de- 
scribed them to produce in the lungs. They partici- 
pate in the process of decay, and are converted into 
carbonates just as in the living body. If impure 
solutions of these salts in water are left exposed 
to the air for any length of time, their acids are 
gradually decomposed, and at length entirely disap- 
pear. 

Free mineral acids, or organic acids which are not 
volatile, and salts of mineral acids with alkaline 
bases, completely arrest decay w^hen added to decay- 
ing matter in sufficient quantity; and w^hen their 
quantity is small, the process of decay is protracted 
and retarded. They produce in living bodies the 
same phenomena as the neutral organic salts, but 
their action depends upon a different cause. 

The absorption by the blood of a quantity of an 
inorganic salt sufficient to arrest the process of 
eremacausis in the lungs, is prevented by a very 
remarkable property of all animal membranes, skin, 
cellular tissue, muscular fibre, &c. ; namely, by their 
incapability of being permeated by concentrated 
saline solutions. It is only when these solutions 
are diluted to a certain degree with water that they 
are absorbed by animal tissues. 

A dry bladder remains more or less dry in satu- 
rated solutions of common salt, nitre, ferro-cyanuret 
of potassium, sulpho-cyanuret of potassium, sulphate 
of magnesia, chloride of potassium, and sulphate of 
soda. These solutions run off its surface in the 
same manner as water runs from a plate of glass 
besmeared with tallow. 



EFFECTS OF SALTS ON THE ORGANISM. 377 

Fresh flesh, over which salt has heeri strewed, is 
found after 24 hours' swimming in brine, although 
not a drop of water has been added. The water 
has been yielded by muscular fibre itself, and having 
dissolved the salt in immediate contact with it, and 
thereby lost the power of penetrating animal sub- 
stances, it has on this account separated from the 
flesh. The water still retained by the flesh contains 
a proportionally small quantity of salt, having that 
degree of dilution at which a saline fluid is capable 
of penetrating animal substances. 

This property of animal tissues is taken advantage 
of in domestic economy for the purpose of removing 
so much water from meat that a sufficient quantity is 
not left to enable it to enter into putrefaction. 

In respect of this physical property of animal 
tissues, alcohol resembles the inorganic salts. It is 
incapable of moistening, that is, of penetrating, ani- 
mal tissues, and possesses such an affinity for water 
as to extract it from moist substances. 

When a solution of a salt, in a certain degree of 
dilution, is introduced into the stomach, it is ab- 
sorbed ; but a concentrated saline solution, in place 
of being itself absorbed, extracts water from the 
organ, and a violent thirst ensues. Some inter- 
change of water and salt takes place in the stomach ; 
the coats of this viscus yield water t6 the solution, 
a part of which having previously become sufficiently 
diluted, is, on the other hand, absorbed. But the 
greater part of the concentrated solution of salt 
remains unabsorbed, and is not removed by the 
urinary passages ; it consequently enters the intes- 
tines and intestinal canal, where it causes a dilution 
of the solid substances deposited there, and thus 
acts as a purg-ative. 

Each of the salts just mentioned possesses this 
purgative action, which depends on a physical prop- 
erty shared by all of them 5 but besides this they 
exercise a medicinal action, because every part of 
32* 



378 POISONS, CONTAGIONS, ML\SMS. 

the organism with which they come in contact ab- 
sorbs a certain quantity of them. 

The composition of the salts has nothing to do 
with their purgative action; it is quite a matter of 
indifference as far as the mere production of this 
action is concerned (not as to its intensity), whether 
the base be potash or soda, or in many cases lime 
and magnesia; and whether the acid be phosphoric, 
sulphuric, nitric, or h}^drochloric. 

Besides, these salts, the action of which does not 
depend upon their power of entering into combina- 
tion with the component parts of the organism, there 
is a large class of others which, w^hen introduced 
into the living body effect changes of a very different 
kind, and produce diseases or death, according to 
the nature of these changes, without effecting a 
visible lesion of any organs. 

These are the true inorganic poisons, the action 
of which depends upon their power of forming per- 
manent compounds with the substance of the mem- 
branes, and muscular fibre. 

Salts of lead, iron, bismuth, copper, and mercury, 
belong to this class. 

When solutions of these salts are treated with a 
sufficient quantity of albumen, milk, muscular fibre, 
and animal membranes, they enter into combination 
with those substances, and lose their own solubility ; 
while the water in which they were dissolved loses 
all the salt which it contained. 

The salts of alkaline bases extract water from 
animal substances; whilst the salts of the heavy 
metallic oxides are, on the contrary, extracted from 
the water, for they enter into combination with the 
animal matters. 

Now, when these substances are administered to 
an animal, they lose their solubility by entering into 
combination with the membranes, cellular tissue, and 
muscular fibre; but in very few cases can they reach 
the blood. All experiments instituted for the pur- 
pose of determining whether they pass into the urine 



INORGANIC POISONS. 379 

have failed to detect them in that secretion. In fact, 
during their passage through the organism, they 
come into contact with many substances by which 
they are retained. 

The action of corrosive sublimate and arsenious 
acid is very remarkable in this respect. It is known 
that these substances possess, in an eminent degree, 
the property of entering into combination with all 
parts of animal and vegetable bodies, rendering them 
at the same time insusceptible of decay or putrefac- 
tion. Wood and cerebral substance are both bodies 
which undergo change with great rapidity and facili- 
ty when subject to the influence of air and water; 
but if they are digested for some time with arsenious 
acid or corrosive sublimate, they may subsequently 
be exposed to all the influences of the atmosphere 
without altering in color or appearance. 

It is further known, that those parts of a body 
which come in contact with these substances during 
poisoning, and which therefore enter into combina- 
tion with them, do not afterwards putrefy ; so that 
there can be no doubt regarding the cause of their 
poisonous qualities. 

It is obvious, that if arsenious acid and corrosive 
sublimate are not prevented by the vital principle 
from entering into combination with the component 
parts of the body, and consequently from rendering 
them incapable of decay and putrefaction, they must 
deprive the organs of the principal property which 
appertains to their vital condition, viz. that of suffer- 
ing and eff"ecting transformations ; or, in other words, 
organic life must be destroyed. If the poisoning is 
merely superficial, and the quantity of the poison so 
small that only individual parts of the body which 
are capable of being regenerated have entered into 
combination with it, then eschars are produced, — a 
phenomenon of a secondary kind, — the compounds 
of the dead tissues with the poison being thrown off 
by the healthy parts. From these consideration's it 
may readily be inferred, that all internal signs of 



380 POISONS, CONTAGIONS, MIASMS. 

poisoning are variable and uncertain; for cases may 
happen, in which no apparent indication of change 
can be detected by simple observations of the parts, 
because, as has been already remarked, death may 
occur without the destruction of any organs. 

When arsenious acid is administered in solution, 
it may enter into the blood. If a vein is exposed 
and surrounded with a solution of this acid, every 
blood-globule will combine with it, that is, will be- 
come poisoned. 

The compounds of arsenic, which have not the 
property of entering into combination with the tis- 
sues of, the organism, are without influence on life, 
even in large doses. Many insoluble basic salts of 
arsenious acid are known not to be poisonous. The 
substance called alkargen, discovered by Bunsen, 
has not the slightest injurious action upon the organ- 
ism ; yet it contains a very large quantity of arsenic, 
and approaches very closely in composition to the 
organic arsenious compounds found in the body. 

These considerations enable us to fix with tolera- 
ble certainty the limit at which the above substances 
cease to act as poisons. For since their combina- 
tion with organic matters must be regulated by 
chemical laws, death will inevitably result, when the 
organ in contact w4th the poison finds sufficient of it 
to unite with atom for atom; whilst if the poison is 
present in smaller quantity, a part of the organ will 
retain its vital functions. 

According to the experiments of Mulder,* the 
equivalent in which fibrin combines with muriatic 
acid, and with the oxides of lead and copper, is 
expressed by the number 6361. It may be assumed, 
therefore, approximatively, that a quantity of fibrin 
corresponding to the number 6361 combines with 1 
equivalent of arsenious acid, or 1 equivalent of cor- 
rosive sublimate. 

When 6361 parts of anhydrous fibrin are combined 

* PoggendorfTs Annalen, Band xl. S. 259. 



INORGANIC POISONS. 381 

with 30,000 parts of water, it is in the state in which 
it is contained in muscular fibre or blood in the 
human body. 100 grains of fibrin in this condition 
would form a neutral compound of equal equivalents 
w^ith 3j^o grains of arsenious acid, and 5 grains of 
corrosive sublimate. 

The atomic weight of the albumen of eggs and of 
the blood deduced from the analysis of the compound 
which it forms with oxide of silver is 7447, and that 
of animal gelatin 5652. 

100 grains of albumen containing all the water 
with which it is combined in the living body, should 
consequently combine with I5 grain of arsenious 
acid. 

These proportions, which may be considered as 
the highest which can be adopted, indicate the re- 
markably high atomic weights of animal substances, 
and at the same time teach us, what very small quan- 
tities of arsenious acid or corrosive sublimate are 
requisite to produce deadly eflfects. 

All substances administered as antidotes in cases 
of poisoning, act by destroying the power which 
arsenious acid and corrosive sublimate possess, of 
entering into combination with animal matters, and 
of thus acting as poisons. Unfortunately no other 
body surpasses them in that power, and the com- 
pounds which they form can only be broken up by 
affinities so energetic, that their action is as injuri- 
ous as that of the above-named poisons themselves. 
The duty of the physician' consists, therefore, in his 
causing those parts of the poison which may be free 
and still uncombined, to enter into combination with 
some other body, so as to produce a compound inca- 
pable of being decomposed or digested in the same 
conditions. Hydrated peroxide of iron is an inval- 
uable substance for this purpose.* 

When the action of arsenious acid or corrosive 
sublimate is confined to the surface of an organ, 

* On the preparation, »&c., of this antidote, see Appendix. 



382 POISONS, CONTAGIONS, MIASMS. 

those parts only are destroyed which enter into com- 
bination with it; an eschar is formed, which is grad- 
ually thrown off. 

Soluble salts of silver would be quite as deadly a 
poison as corrosive sublimate, did not a cause exist 
in the human body by which their action is prevented, 
unless their quantity is very great. This cause is 
the presence of common salt in all animal liquids. 
Nitrate of silver, it is well known, combines with 
animal substances, in the same manner as corrosive 
sublimate, and the compounds formed by both are 
exactly similar in the character of being incapable 
of decay or putrefaction. 

When nitrate of silver in a state of solution is 
applied to skin or muscular fibre, it combines with 
them instantaneously; animal substances dissolved 
in any liquid are precipitated by it, and rendered 
insoluble, or, as it is usually termed, they are coagu- 
lated. The compounds thus formed are colorless, 
and so stable, that they cannot be decomposed by 
other powerful chemical agents. They are blackened 
by exposure to light, like all other compounds of 
silver, in consequence of a part of the oxide of silver 
which they contain being reduced to the metallic 
state. Parts of the body which have united with 
salts of silver no longer belong to the living organ- 
ism, for their vital functions have been arrested by 
combination with oxide of silver ; and if they are 
capable of being reproduced, the neighboring living 
structures throw them off in the form of an eschar. 

When nitrate of silver is introduced into the 
stomach, it meets with common salt and free muriatic 
acid ; and if its quantity is not too great, it is im- 
mediately converted into chloride of silver, — a sub- 
stance which is absolutely insoluble in pure water. 
In a solution of salt or muriatic acid, however, 
chloride of silver does dissolve in extremely minute 
quantity; and it is this small part which exercises 
a medicinal influence when nitrate of silver is admin- 
istered ; the remaining chloride of silver is elimi- 



INORGANIC POISONS. 383 

nated from the body in the ordinary way. Solubility 
is necessary to give efficacy to any substance in the 
human body. 

The soluble salts of lead possess many properties 
in common with the salts of silver and mercury; but 
all compounds of lead with organic matters are 
capable of decomposition by dilute sulphuric acid. 
The disease called painter''s colic is unknown in all 
manufactories of white lead in which the workmen 
are accustomed to take as a preservative sulphuric 
acid-lemonade (a solution of sugar rendered acid by 
sulphuric acid). 

The organic substances which have combined in 
the living body with metallic oxides or metallic salts, 
lose their property of imbibing water and retaining 
it, without at ths same time being rendered incapa- 
ble of permitting liquids to penetrate through their 
pores. A strong contraction and shrinking of the 
surface is the general effect of contact with these 
metallic bodies. But corrosive sublimate, and several 
of the salts of lead, possess a peculiar property, in 
addition to those already mentioned. When they are 
present in excess, they dissolve the first formed 
insoluble compounds, and thus produce an effect 
quite the reverse of contraction, namely, a softening 
of the part of the body on which they have acted. 

Salts of oxide of copper, even when in combina- 
tion with the most powerful acids, are reduced by 
many vegetable substances, particularly such as sugar 
and honey, either into metallic copper, or into the 
red suboxide, neither of which enters into combina- 
tion with animal matter. It is well known that sugar 
has been long employed as the most convenient 
antidote for poisoning by copper. 

With respect to some other poisons, namely, hy- 
drocyanic acid and the organic bases strychnia and 
brucia, we are acquainted with no facts calculated to 
elucidate the nature of their action. It may, how- 
ever, be presumed with much certainty, that experi- 
ments upon their mode of action on different animal 



384 POISONS, CONTAGIONS, MIASMS. 

substances would very quickly lead to the most 
satisfactory conclusions regarding the cause of their 
poisonous effects. 

There is a peculiar class of substances, which are 
generated during certain processes of decomposition, 
and which act upon the animal economy as deadly 
poisons, not on account of their power of entering 
into combination with it, or by reason of their con- 
taining a poisonous material, but solely by virtue of 
their peculiar condition. 

In order to attain a clear conception of the mode 
of action of these bodies, it is necessai'y to call to 
mind the cause on which we have shown the phe- 
nomena of fermentation, decay, and putrefaction to 
depend. 

This cause may be expressed by the following 
law, long since proposed by La Place and Berthollet, 
although its truth with respect to chemical phenom- 
ena has only lately been proved. " A molecule set 
in motion by any poiver can impart its own motion to 
another molecule with which it may he in contact^ 

This is a law of dynamics, the operation of which 
is manifest in all cases, in which the resistance 
{^force, affinity, or cohesion^ opposed to the motion is 
not sufficient to overcome it. 

We have seen that ferment or yeast is a body in 
the state of decomposition, the atoms of which, con- 
sequently, are in a state of motion or transposition- 
Yeast placed in contact with sugar communicates to 
the elements of that compound the same state, in 
consequence of which, the constituents of the sugar 
arrange themselves into new and simpler forms, 
namely, into alcohol and carbonic acid. In these 
new compounds the elements are united together by 
stronger affinities than they were in the sugar, and 
therefore under the conditions in which they were 
produced further decomposition is arrested. 

We know, also, that the elements of sugar assume 
totally different arrangements, when the substances 
which excite their transposition are in a different 



PUTRID POISONS. 385 

state of decomposition from the yeast just mentioned. 
Thus, when sugar is acted on by rennet or putrefy- 
ing vegetable juices, it is not converted into alcohol 
and carbonic acid, but into lactic acid, mannite, and 
gum. 

Again, it has been shown, that yeast added to a 
solution of pure sugar gradually disappears, but that 
when added to vegetable juices which contain gluten 
as well as sugar, it is reproduced by the decomposi- 
tion of the former substance. 

The yeast with which these liquids are made to 
ferment, has itself been originally produced from 
gluten. 

The conversion of gluten into yeast in these veg- 
etable juices is dependent on the decomposition 
(fermentation) of sugar ; for, when the sugar has 
completely disappeared, any gluten which may still 
remain in the liquid does not suffer change from 
contact with the newly-deposited yeast, but retains 
all the characters of gluten. 

Yeast is a product of the decomposition of gluten; 
but it passes into a second stage of decomposition 
when in contact with water. On account of its being 
in this state of further change, yeast excites fermen- 
tation in a fresh solution of sugar, and if this second 
saccharine fluid should contain gluten, (should it be 
wort, for example,) yeast is again generated in con- 
sequence of the transposition of the elements of the 
sugar exciting a similar change in this gluten. 

After this explanation, the idea that yeast repro- 
duces itself as seeds reproduce seeds, cannot for a 
moment be entertained. 

From the foregoing facts it follows, that a body 
.in the act of decomposition (it may be named the 
exciter), added to a mixed fluid in which its constit- 
uents are contained, can reproduce itself in that 
fluid, exactly in the same manner as new yeast is 
produced when yeast is added to liquids containing 
gluten. This must be more certainly effected when 
the liquid acted upon contains the body by the met- 
33 



386 POISONS, CONTAGIONS, MIASMS. 

araorphosis of which the exciter has been originally 
formed. 

It is also obvious, that if the exciter be able to 
impart its own state of transformation to one only 
of the component parts of the mixed liquid acted 
upon, its own reproduction may be the consequence 
of the decomposition of this one body. 

This law may be applied to organic substances 
forming part of the animal organism. We know that 
all the constituents of these substances are formed 
from the blood, and that the blood by its nature and 
constitution is one of the most complex of all exist- 
ing matters. 

Nature has adapted the blood for the reproduction 
of every individual part of the organism; its princi- 
pal character consists in its component parts being 
subordinate to every attraction. These are in a per- 
petual state of change or transformation, which is 
etfected in the most various ways through the in- 
fluence of the different organs. 

The individual organs, such as the stomach, cause 
all the organic substances conveyed to them which 
are capable of transformation to assume new forms. 
The stomach compels the elements of these sub- 
stances to unite into a compound fitted for the for- 
mation of the blood. But the blood possesses no 
power of causing transformations ; on the contrary, 
its principal character consists in its readily suffering 
transformations ; and no other matter can be com- 
pared in this respect with it. 

Now it is a well-known fact, that when blood, 
cerebral substance, gall, pus, and other substances 
in a state of putrefaction, are laid upon fresh 
wounds, vomiting, debility, and at length death, 
are occasioned. It is also well known, that bodies 
in anatomical rooms frequently pass into a state of 
decomposition which is capable of imparting itself 
to the living body, the smallest cut with a knife, 
which has been used in their dissection, producing 
in these cases dangerous consequences. 



PUTRID POISONS. 387 

The poison of bad sausages belongs to this class 
of noxious substances. Several hundred cases are 
known in which death has occurred from the use of 
this kind of food. In Wiirtcmberg, especially, these 
cases are very frequent, for there the sausages are 
prepared from very various materials. Blood, liver, 
bacon, brains, milk, meal, and bread, are mixed to- 
gether with salt and spices ; the mixture is then put 
into bladders or intestines, and after being boiled is 
smoked. 

When these sausages are well prepared, they may 
be preserved for months, and furnish a nourishing, 
savoury food; but when the spices and salt are de- 
ficient, and particularly when they are smoked too 
late or not sufficiently, they undergo a peculiar kind 
of putrefaction, which begins at the centre of the 
sausage. Without any appreciable escape of gas 
taking place they become paler in color, and more 
soft and greasy in those parts which have under- 
gone putrefaction, and they are found to contain free 
lactic acid, or lactate of ammonia, products which 
are universally formed during the putrefaction of 
animal and vegetable matters. 

The cause of the poisonous nature of these sau- 
sages was ascribed at first to hydrocyanic acid, and 
afterwards to sebacic acid, although neither of these 
substances had been detected in them. But sebacic 
acid is no more poisonous than benzoic acid, with 
which it has so many properties in common; and the 
symptoms produced are sufficient to show that hy- 
drocyanic acid is not the poison. 

The death which is the consequence of poisoning 
by putrefied sausages succeeds very lingering and 
remarkable symptoms. There is a gradual wasting 
of muscular fibre, and of all the constituents of the 
body similarly composed; the patient becomes much 
emaciated, dries to a complete mummy, and finally 
dies. The carcass is stiff as if frozen, and is not 
subject to putrefaction. During the progress of the 



388 POISONS, CONTAGIONS, MIASMS. 

disease the saliva becomes viscous and acquires an 
offensive smell. 

Experiments have been made for the purpose of 
ascertaining the presence of some matter in the 
sausages to which their poisonous action could be 
ascribed; but no such matter has been detected. 
Boiling water and alcohol completely destroy the 
poisonous properties of the sausages, without them- 
selves acquiring similar properties. 

Now this is the peculiar character of all substances 
which exert an action by virtue of their existing 
condition, — of those bodies the elements of which 
are in the state of decomposition or transposition; a 
state which is destroyed by boiling water and alco- 
hol without the cause of the influence being imparted 
to those liquids ; for a state of action or power can- 
not be preserved in a liquid. 

Sausages, in the state here described, exercise an 
action upon the organism, in consequence of the 
stomach and other parts with which they come in 
contact not having the power to arrest their decom- 
position ; and entering the blood in some way or 
other, while still possessing their whole power, they 
impart their peculiar action to the constituents of 
that fluid. 

The poisonous properties of decayed sausages are 
not destroyed by the stomach as those of the small- 
pox virus are. All the substances in the body capa- 
ble of putrefaction are gradually decomposed during 
the course of the disease, and after death nothing 
remains except fat, tendons, bones, and a few other 
substances, which are incapable of putrefying in the 
conditions afforded by the body. 

It is impossible to mistake the modus operandi of 
this poison, for Colin has clearly proved that mus- 
cle, urine, cheese, cerebral substance, and other 
matters, in a state of putrefaction, communicate 
their own state of decomposition to substances much 
less prone to change of composition than the blood. 
When placed in contact with a solution of sugar, 



MORBID POISONS. 389 

they cause its putrefaction, or the transposition of 
its elements into carbonic acid and alcohol. 

When putrefying muscle or pus is placed upon a 
fresh ViTound, it occasions disease and death. It is 
obvious that these substances communicate their 
own state of putrefaction to the sound blood from 
lohich they lo ere produced, exactly in the same man- 
ner as gluten in a state of decay or putrefaction 
causes a similar transformation in a solution of 
sugar. 

Poisons of this kind are even generated by the 
body itself in particular diseases. In small-pox, 
plague, and syphilis, substances of a peculiar na- 
ture are formed from the constituents of the blood. 
These matters are capable of inducing in the blood 
of a healthy individual a decomposition similar to 
that of which they themselves are the subjects ; in 
other words, they produce the same disease. The 
morbid virus appears to reproduce itself just as seeds 
appear to reproduce seeds. 

The mode of action of a morbid virus exhibits 
such a strong similarity to the action of yeast upon 
liquids containing sugar and gluten, that the two 
processes have been long since compared to one 
another, although merely for the purpose of illustra- 
tion. But when the phenomena attending the action 
of each respectively are considered more closely, it 
will in reality be seen that their influence depends 
upon the same cause. 

In dry air, and in the absence of moisture, all 
these poisons remain for a long time unchanged; but 
when exposed to the air in the moist condition, they 
lose very rapidly their peculiar properties. In the 
former case, those conditions are afforded which 
arrest their decomposition without destroying it ; 
in the latter, all the circumstances necessary for the 
completion of their decomposition are presented. 

The temperature at which water boils, and contact 
with alcohol, render such poisons inert. Acids, salts 
of mercury, sulphurous acid, chlorine, iodine, bro- 
33* 



390 POISONS, CONTAGIONS, MIASMS. 

mine, aromatic substances, volatile oils, and partic- 
ularly empyreumatic oils, smoke, and a decoction of 
coffee, completely destroy their contagious properties, 
in some cases combining with them or otherwise 
effecting their decomposition. Now all these agents, 
without exception, retard fermentation, putrefaction 
and decay, and when present in sufficient quantity, 
completely arrest these processes of decomposition. 

A peculiar matter to which the poisonous action 
is due, cannot, we have seen, be extracted from 
decayed sausages; and it is equally impossible to 
obtain such a principle from the virus of small-pox 
or plague, and for this reason, that their peculiar 
power is due to an active condition recognisable by 
our senses, only through the phenomena which it 
produces. 

In order to explain the effects of contagious mat- 
ters, a peculiar principle of life has been ascribed to 
them, — a life similar to that possessed by the germ 
of a seed, which enables it under favorable condi- 
tions to develop and multiply itself. It would be 
impossible to find a more correct figurative repre- 
sentation of these phenomena ; it is one which is 
applicable to contagions, as well as to ferment, to 
animal and vegetable substances in a state of fer- 
mentation, putrefaction or decay, and even to a piece 
of decaying wood, which by mere contact with fresh 
wood, causes the latter to undergo gradually the 
same change and become decayed and mouldered. 

If the property possessed by a body of producing 
such a change in any other substance as causes the 
reproduction of itself, with all its properties, be 
regarded as life, then, indeed, all the above phenom- 
ena may be ascribed to life. But in that case they 
must not be considered as the only processes due to 
vitality, for the above interpretation of the expres- 
sion embraces the majority of the phenomena which 
occur in organic chemistry. Life would, according 
to that view, be admitted to exist in every body in 
which chemical forces act. 



MORBID POISONS. 391 

If a body A, for example oxamide (a substance 
scarcely soluble in water, and without the slightest 
taste), be brought into contact with another com- 
pound B, which is to be reproduced; and if this 
second body be oxalic acid dissolved in water; then 
the following changes are observed to take place: — 
The oxamide is decomposed by the oxalic acid, 
provided the conditions necessary for their exercis- 
ing an action upon one another are present. The 
elements of water unite with the constituents of 
oxamide, and ammonia is one product formed, and 
oxalic acid the other, both in exactly the proper 
proportions to combine and form a neutral salt. 

Here the contact of oxamide and oxalic acid induces 
a transformation of the oxamide, which is decomposed 
into oxalic acid and ammonia. The oxalic acid thus 
formed, as well as that originally added, are shared 
by the ammonia, — or in other w^ords, as much free 
oxalic acid exists after the decomposition as before 
it, and is of course still possessed of its original 
power. It matters not whether the free oxalic acid 
is that originally added, or that newly produced ; it 
is certain that it has been reproduced in an equal 
quantity by the decomposition. 

If we now add to the same mixture a fresh portion 
of oxamide, exactly equal in quantity to that first 
used, and treat it in the same manner, the same 
decomposition is repeated ; the free oxalic acid en- 
ters into combination, whilst another portion is 
liberated. In this manner a very minute quantity 
of oxalic acid may be made to effect the decomposi- 
tion of several hundred pounds of oxamide ; and 
one grain of the acid to reproduce itself in unlimited 
quantity. 

We know that the contact of the virus of small- 
pox causes such a change in the blood, as gives rise 
to the reproduction of the poison from the constitu- 
ents of the fluid. This transformation is not arrested 
until all the particles of the blood which are suscep- 
tible of the decomposition have undergone the met- 



392 POISONS, CONTAGIONS, MIASMS. 

amorphosis. We have just seen that the contact of 
oxalic acid with oxamide caused the production of 
fresh oxalic acid, which in its turn exercised the 
same action on a new portion of oxamide. The 
transformation was only arrested in consequence of 
the quantity of oxamide present being limited. In 
their form both these transformations belong to the 
same class. But no one except a person quite unac- 
customed to view such changes will ascribe them to 
a vital power, although w^e admit they correspond 
remarkably to our common conceptions of life ; they 
are really chemical processes dependent upon the 
common chemical forces. 

Our notion of life involves something more than 
mere reproduction, namely, the idea of an active 
power exercised by virtue of a definite form, and 
production and generation in a definite form. By 
chemical agency we can produce the constituents of 
muscular fibre, skin, and hair ; but we can form by 
their means no organized tissue, no organic cell. 

The production of organs, the cooperation of a 
system of organs, and their power not only to pro- 
duce their component parts from the food presented 
to them, but to generate themselves in their original 
form and with all their properties, are characters 
belonging exclusively to organic life, and constitute 
a form of reproduction independent of chemical 
powers. 

The chemical forces are subject to the invisible 
cause by which this form is produced. Of the exist- 
ence of this cause itself we are made aware only by 
the phenomena which it produces. Its laws must be 
investigated just as we investigate those of the other 
powers which effect motion and changes in matter. 

The chemical forces are subordinate to this cause 
of life, just as they are to electricity, heat, mechan- 
ical motion, and friction. By the influence of the 
latter forces, they suffer changes in their direction, 
an increase or diminution of their intensity, or a 
complete cessation or reversal of their action. 



THEIR MODE OF ACTION. 393 

Such an influence and no other is exercised by the 
vital principle over the chemical forces ; but in every 
case where combination or decomposition takes 
place, chemical affinity and cohesion are in action. 

The vital principle is only known to us through 
the peculiar form of its instruments, that is, through 
the organs in which it resides. Hence, whatever 
kind of energy a substance may possess, if it is 
amorphous and destitute of organs from which the 
impulse, motion or change proceeds, it does not live. 
Its energy depends in this case on a chemical action. 
Light, heat, electricity, or other influences may in- 
crease, diminish, or arrest this action, but they are 
not its efficient cause. 

In the same way the vital principle governs the 
chemical powers in the living body. All those sub- 
stances to which we apply the general name of food, 
and all the bodies formed from them in the organism, 
are chemical compounds. The vital principle has, 
therefore, no other resistance to overcome, in order 
to convert these substances into component parts of 
the organism, than the chemical powers by which 
their constituents are held together. If the food pos- 
sessed life, not merely the chemical forces, but this 
vitality, would offer resistance to the vital force of 
the organism it nourished. 

All substances adapted for assimilation are bodies 
of a very complex constitution ; their atoms are 
highly complex, and are held together only by a 
weak chemical action. They are formed by the union 
of two or more simple compounds ; and in propor- 
tion as the number of their atoms augments, their 
disposition to enter into new combinations is dimin- 
ished ; that is, they lose the power of acting chem- 
ically upon other bodies. 

Their complex nature, however, renders them 
more liable to be changed, by the agency of external 
causes, and thus to suffer decomposition. Any ex- 
ternal agency, in many cases even mechanical friction, 
is sufficient to cause a disturbance in the equilibrium 



394 POISONS, CONTAGIONS, MIASMS. 

of the attraction of their constituents ; they arrange 
themselves either into new, more simple, and perma- 
nent combinations, or if a foreign attraction exercise 
its influence upon it, they arrange themselves in 
accordance with that attraction. 

The special characters of food, that is, of substan- 
ces fitted for assimilation, are absence of active 
chemical properties, and the capability of yielding 
to transformations. 

The equilibrium in the chemical attractions of the 
constituents of the food is disturbed by the vital 
principle, as we know it may be by many other causes. 
But the union of its elements, so as to produce new 
combinations and forms, indicates the presence of a 
peculiar mode of attraction, and the existence of a 
power distinct from all other powers of nature, 
namely, the vital principle. 

All bodies of simple composition possess a greater 
or less disposition to form combinations. Thus oxalic 
acid is one of the simplest of the organic acids, 
while stearic acid is one of the most complex; and 
the former is the strongest, the latter one of the 
weakest, in respect to active chemical character. By 
virtue of this disposition, simple compounds produce 
changes in every body which offers no resistance to 
their action ; they enter into combination and cause 
decomposition. 

The vital principle opposes to the continual action 
of the atmosphere, moisture and temperature upon 
the organism, a resistance which is, in a certain 
degree, invincible. It is by the constant neutraliza- 
tion and renewal of these external influences that 
life and motion are maintained. 

The greatest wonder in the living organism is the 
fact, that an unfathomable wisdom has made the 
cause of a continual decomposition or destruction, 
namely, the support of the process of respiration, 
to be the means of renewing the organism, and of 
resisting all the other atmospheric influences, such 
as those of moisture and changes of temperature. 



• THEIR MODE OF ACTION. 395 

When a chemical compound of simple constitution 
is introduced into the stomach, or any other part of 
the organism, it must exercise a chemical action 
upon all substances with which it comes in contact ; 
for we know the peculiar character of such a body 
to be an aptitude and power to enter into combina- 
tions and effect decompositions. 

The chemical action of such a compound is of 
course opposed by the vital principle. The results 
produced depend upon the strength of their respec- 
tive actions ; either an equilibrium of both powers is 
attained, a change being effected without the de- 
struction of the vital principle, in which case a medi- 
cinal effect \'^ occasioned; or the acting body yields 
to the superior force of vitality, that \'&^itis digested ; 
or lastly, the chemical action obtains the ascendency 
and acts as a poison. 

Every substance may be considered as nutriment, 
which loses its former properties when acted on by 
the vital principle, and does not exercise a chemical 
action upon the living organ. 

Bodies of another class change the direction, the 
strength, and intensity of the resisting force (the 
vital principle), and thus exert a modifying influence 
upon the functions of its organs. They produce a 
disturbance in the system, either by their presence, 
or by themselves undergoing a change; these are 
medicaments. 

Compounds of a third class are called poisons, 
when they possess the property of uniting with or- 
gans or with their component parts, and when their 
power of effecting this is stronger than the resis- 
tance offered by the vital principle. 

The quantity of a substance and its condition must 
obviously completely change the mode of its chemi- 
cal action. 

Increase of quantity is known to be equivalent to 
superior affinity. Hence a medicament administered 
in excessive quantity may act as a poison, and a 
poison in small doses as a medicam,ent. 



396 POISONS, CONTAGIONS, MIASMS. 

Food will act as a poison, that is, it will produce 
disease, when it is able to exercise a chemical action 
by virtue of its quantity; or, when either its con- 
dition or its presence retards, prevents, or arrests 
the motion of any organ. 

A compound acts as a poison when all the parts 
of an organ with which it is brought into contact 
enter into chemical combination with it, while it may 
operate as a medicine, when it produces only a par- 
tial change. 

No other component part of the organism can be 
compared to the blood, in respect of the feeble re- 
sistance which it offers to exterior influences. The 
blood is not an organ which is formed, but an organ 
in the act of formation ; indeed, it is the sum of all 
the organs which are being formed. The chemical 
force and the vital principle hold each other in such 
perfect equilibrium, that every disturbance, however 
trifling, or from whatever cause it may proceed, effects 
a change in the blood. This liquid possesses so 
little of permanence, that it cannot be removed from 
the body without immediately suffering a change, 
and cannot come in contact with any organ in the 
body, without yielding to its attraction. 

The slightest action of a chemical agent upon the 
blood exercises an injurious influence; even the mo- 
mentary contact with the air in the lungs, although 
effected through the medium of cells and membranes, 
alters the color and other qualities of the blood. 
Every chemical action propagates itself through the 
mass of the blood; for example, the active chemical 
condition of the constituents of a body undergoing 
decomposition, fermentation, putrefaction, or decay, 
disturbs the equilibrium between the chemical force 
and the vital principle in the circulating fluid. 
Numerous modifications in the composition and con- 
dition of the compounds produced from the elements 
of the blood, result from the conflict of the vital 
force wnth the chemical affinity, in their incessant 
endeavor to overcome one another. 



THEIR MODE OF ACTION. 397 

All the characters of the phenomena of contagion 
tend to disprove the existence of life in contagious 
matters. They without doubt exercise an influence 
very similar to some processes in the living organ- 
ism; but the cause of this influence is chemical 
action, which is capable of being subdued by other 
chemical actions, by opposed agencies. 

Several of the poisons generated in the body by 
disease lose all their power when introduced into 
the stomach, but others are not thus destroyed. 

It is a fact very decisive of their chemical nature 
and mode of action, that those poisons which are 
neutral or alkaline, such as the poisonous matter of 
the contagious fever in cattle [typhus contagiosiis 
rvminantium), or that of the smallpox, lose their 
whole power of contagion in the stomach ; whilst 
that of sausages, which has an acid reaction, retains 
all its frightful properties under the same circum- 
stances. 

In the former of these cases, the free acid present 
in the stomach destroys the action of the poison, 
the chemical properties of which are opposed to it; 
whilst in the latter it strengthens, or at all events 
does not offer any impediment to poisonous action. 

Microscopical examination has detected peculiar 
bodies resembling the globules of the blood in ma- 
lignant putrefying pus, in the matter of vaccine, &c. 
The presence of these bodies has given weight to 
the opinion, that contagion proceeds from the de- 
velopment of a diseased organic life ; and these for- 
mations have been regarded as the living seeds of 
disease. 

This view, which is not adapted to discussion, has 
led those philosophers, who are accustomed to search 
for explanations of phenomena in forms, to consider 
the yeast produced by the fermentation of beer as 
possessed of life. They have imagined it to be com- 
posed of animals or plants, which nourish themselves 
from the sugar in which they are placed, and at the 
34 



398 POISONS, CONTAGIONS, MIASMS. 

same time yield alcohol and carbonic acid as excre- 
mentitious matters.* 

It would perhaps appear wonderful if bodies, pos- 
sessing a crystalline structure and geometrical figure, 
were formed during the processes of fermentation 
and putrefaction from the organic substances and 
tissues of organs. We know, on the contrary, that 
the complete dissolution into organic compounds is 
preceded by a series of transformations, in which 
the organic structures gradually resign their forms. 

Blood, in a state of decomposition may appear to 
the eye unchanged j and when we recognise the 
globules of blood in a liquid contagious matter, the 
utmost that we can thence infer is, that those glob- 
ules have taken no part in the process of decompo- 
sition. All the phosphate of lime may be removed 
from bones, leaving them transparent and flexible 
like leather, without the form of the bones being in 
the smallest degree lost. Again, bones may be 
burned until they be quite white, and consist merely 
of a skeleton of phosphate of lime, but they will still 
possess their original form. In the same way pro- 
cesses of decomposition in the blood may affect in- 
dividual constituents only of that fluid, which will 
become destroyed and disappear, whilst its other 
parts will maintain the original form. 

Several kinds of contagion are propagated through 
the air: so that, according to the view already 
mentioned, we must ascribe life to a gas, that is, to 
an aeriform body. 

All the supposed proofs of the vitality of con- 
tagions are merely ideas and figurative representa- 
tions, fitted to render the phenomena more easy of 
apprehension by our senses, without explaining them 
These figurative expressions, with which we are so 
willingly and easily satisfied in all sciences, are the 
foes of all inquiries into the mysteries of nature ; they 
are like the/ato morgana, which show us deceitful 

* Annalen der Pharmacie, Band xxix. S. 93 und 100. 



THEIR MODE OF ACTION. 399 

views of seas, fertile fields, and luscious fruits, but 
leave us lano-uishino; when we have most need of 
what they promise. 

It is certain, that the action of contagions is the 
result of a peculiar influence dependent on chemical 
forces, and in no way connected with the vital prin- 
ciple. This influence is destroyed by chemical ac- 
tions, and manifests itself wherever it is not sub- 
dued by some antagonist power. Its existence is 
recognised in a connected series of changes and 
transformations, in which it causes all substances 
capable of undergoing similar changes to participate. 

An animal substance in the act of decomposition, 
or a substance generated from the component parts 
of a living body by disease, communicates its own 
condition to all parts of the system capable of enter- 
ing into the same state, if no cause exist in these 
parts by which the change is counteracted or de- 
stroyed. 

Disease is excited by contagion. 

The transformations produced by the disease as- 
sume a series of forms. 

In order to obtain a clear conception of these 
transformations, we may consider the changes which 
substances, more simply composed than the living 
body, suffer from the influence of similar causes. 
When putrefying blood or yeast in the act of trans- 
formation is placed in contact with a solution of 
sugar, the elements of the latter substance are trans- 
posed, so as to form alcohol and carbonic acid. 

A piece of the rennet-stomach of a calf in a state 
of decomposition occasions the elements of sugar to 
assume a different arrangement. The sugar is con- 
verted into lactic acid without the addition or loss 
of any element. (1 atom of sugar of grapes C12 
H12 012 yields two atoms of lactic acid =2 (C6 
H6 06.) 

When the juice of onions or of beet-root is made 
to ferment at high temperatures, lactic acid, mannite, 
and gum are formed. Thus, according to the differ- 



400 POISONS, CONTAGIONS, MIASMS. 

ent states of the transposition of the elements of the 
exciting body, the elements of the sugar arrange 
themselves in different manners, that is, different 
products are formed. 

The immediate contact of the decomposing sub- 
stance with the sugar is the cause by which its 
particles are made to assume new forms and natures. 
The removal of that substance occasions the cessa- 
tion of the decomposition of the sugar, so that, 
should its transformation be completed before the 
sugar, the latter can suffer no further change. 

In none of these processes of decomposition is 
the exciting body reproduced ; for the conditions 
necessary to its reproduction do not exist in the 
elements of the sugar. 

Just as yeast, putrefying flesh, and the stomach 
of a calf in a state of decomposition, when intro- 
duced into solutions of sugar, effect the transforma- 
tion of this substance, without being themselves re- 
generated ; in the same manner, miasms and certain 
contagious matters produce diseases in the human 
organism, by communicating the state of decompo- 
sition, of which they themselves are the subject, to 
certain parts of the organism, without themselves 
being reproduced in their peculiar form and nature 
during the progress of the decomposition. 

The disease in this case is not contagious. 

Now when yeast is introduced into a mixed liquid 
containing both sugar and gluten, such as wort, the 
act of decomposition of the sugar effects a change 
in the form and nature of the gluten, which is, in 
consequence, also subjected to transformation. As 
long as some of the fermenting sugar remains, gluten 
continues to be separated as yeast, and this new 
matter in its turn excites fermentation in a fresh 
solution of sugar or wort. If the sugar, however, 
should be first decomposed, the gluten which re- 
mains in solution is not converted into yeast. We 
see, therefore, that the reproduction of the exciting 
body here depends, — 



THEIR MODE OF ACTION. 401 

1. Upon the presence of that substance from which 
it was originally formed ; 

2. Upon the presence of a compound which is 
capable of being decomposed by contact with the 
exciting body. 

If we express in the same terms the reproduction 
of contagious matter in contagious diseases, since it 
is quite certain that they must have their origin in 
the blood, we must admit that the blood of a healthy 
individual contains substances, by the decomposition 
of which the exciting body or contagion can be pro- 
duced. It must further be admitted, when contagion 
results, that the blood contains a second constituent 
capable of being decomposed by the exciting body. 
It is only in consequence of the conversion of the 
second constituent, that the original exciting body 
can be reproduced. 

A susceptibility of contagion indicates the pres- 
ence of a certain quantity of this second body in the 
blood of a healthy individual. The susceptibility 
for the disease and its intensity must augment ac- 
cording to the quantity of that body present in the 
blood; and in proportion to its diminution or dis- 
appearance, the course of the disease will change. 

When a quantity, however small, of contagious 
matter, that is, of the exciting body, is introduced 
into the blood of a healthy individual, it will be 
again generated in the blood, just as yeast is repro- 
duced from wort. Its condition of transformation 
will be communicated to a constituent of the blood; 
and in consequence of the transformation suffered by 
this substance, a body identical with or similar to 
the exciting or contagious matter will be produced 
from another constituent substance of the blood. 
The quantity of the exciting body newly produced 
must constantly augment, if its further transforma- 
tion or decomposition proceeds more slowly than 
that of the compound in the blood, the decompo- 
sition of which it effects. 

If the transformation of the yeast generated in 
34* 



402 POISONS, CONTAGIONS, MIASMS. j 

the fermentation of wort proceeded with the same 
•rapidity as that of the particles of the sugar con- 
tained in it, both would simultaneously disappear 
when the fermentation was completed. But yeast 
requires a much 'longer time for decomposition than 
sugar, so that after the latter has completely disap- 
peared, there remains a much larger quantity of 
yeast than existed in the fluid at the commencement 
of the fermentation, — yeast which is still in a state 
of incessant progressive transformation, and there- 
fore possessed of its peculiar property. 

The state of change or decomposition which effects 
one particle of blood, is imparted to a second, a 
third, and at last to all the particles of blood in the 
whole body. It is communicated in like manner to 
the blood of another individual, to that of a third 
person, and so on, — or in other words, the disease 
is excited in them also. 

It is quite certain, that a number of peculiar sub- 
stances exist in the blood of some men and animals, 
which are absent from the blood of others. 

The blood of the same individual contains, in 
childhood and youth, variable quantities of substan- 
ces, which are absent from it in other stages of 
growth. The susceptibility of contagion by peculiar 
exciting bodies in childhood, indicates a propagation 
and regeneration of the exciting bodies, in conse- 
quence of the transformation of certain substances 
which are present in the blood, and in the absence 
of which no contagion could ensue. The form of a 
disease is termed benignant, when the transforma- 
tions are perfected on constituents of the body which 
are not essential to life, without the other parts 
taking a share in the decomposition; it is termed 
malignant when they affect essential organs. 

It cannot be supposed, that the different changes 
in the blood, by which its constituents are converted 
into fat, muscular fibre, substance of the brain and 
nerves, bones, hair, &c., and the transformation of 
food into blood, can take place without the simulta- 



THEIR :\IODE OF ACTION. 403 

neous formation of new compounds which require to 
be removed from the body by the organs of excre- 
tion. 

In an adult these excretions do not vary much 
either in their nature or quantity. The food taken 
is not employed in increasing the size of the body, 
but merely for the purpose of replacing any sub- 
stances which may be consumed by the various 
actions in the organism; every motion, every mani- 
festation of organic properties, and every organic 
action being attended by a change in the material 
of the body, and by the assumption of a new form 
by its constituents.* 

But in a child this normal condition of sustenance 
is accompanied by an abnormal condition of growth 
and increase in the size of the body, and of each 
individual part of it. Hence there must be a much 
larger quantity of foreign substances, not belonging 
to the organism, diffused through every part of the 
blood in the body of a young individual. 

When the organs of secretion are in proper action, 
these substances will be removed from the system ; 
but when the functions of those organs are impeded, 
they will remain in the blood or become accumulated 
in particular parts of the body. The skin, lungs, 
and other organs, assume the functions of the dis- 
eased secreting organs, and the accumulated sub- 
stances are eliminated by them. If, when thus 
exhaled, these substances happen to be in the state 
of progressive transformation, they are contagious ; 
that is, they are able to produce the same state of 
disease in another healthy organism, provided the 
latter organism is susceptible of their action, — or 
in other words, contains a matter capable of suffer- 
ing the same process of decomposition. 

* The experiments of Barruel upon the different odors emitted from 
blood on the addition of sulphuric acid, prove that peculiar substances 
are contained in the blood of different individuals; the blood of a man 
of a fair complexion and that of a man of dark complexion w-ere found 
to yield different odors ; the blood of animals also differed in this respect 
very perceptibly from that of man. — L. 



404 POISONS, CONTAGIONS, MIASMS. 

The production of matters of this kind, which 
render the body susceptible of contagion, may be 
occasioned by the manner of living, or by the nutri- 
ment taken by an individual. A superabundance of 
strong and otherwise wholesome food may produce 
them, as well as a deficiency of nutriment, unclean- 
liness, or even the use of decayed substances as 
food. 

All these conditions for contao-ion must be con- 
. . . ^ . 

sidered as accidental. Their formation and accu- 
mulation in the body may be prevented, and they 
may even be removed from it without disturbing its 
most important functions or health. Their presence 
is not necessary to life. 

The action, as well as the generation of the matter 
of contagion is, according to this view, a chemical 
process participated in by all substances in the 
living body, and by all the constituents of those 
organs in which the vital principle does not over- 
come the chemical action. The contasfion, accord- 
ingly, either spreads itself over every part of the 
body, or is confined particularly to certain organs, 
that is, the disease attacks all the organs or only a 
few of them, according to the feebleness or intensity 
of their resistance. 

In the abstract chemical sense, reproduction of a 
contagion depends upon the presence of two sub- 
stances, one of which becomes completely decom- 
posed, but communicates its own state of transform- 
ation to the second. The second substance thus 
thrown into a state of decomposition is the newly- 
formed contagion. 

The second substance must have been originally a 
constituent of the blood : the first may be a body 
accidentally present; but it may also be a matter 
necessary to life. If both be constituents indispen- 
sable for the support of the vital functions of certain 
principal organs, death is the consequence of their 
transformation. But if the absence of the one sub- 
stance which was a constituent of the blood do not 



THEIR MODE OF ACTION. 405 

cause an immediate cessation of the functions of 
the most important organs, if they continue in their 
action, although in an abnormal condition, conval- 
escence ensues. In this case the products of the 
transformations still existing in the blood are used 
for assimilation, and at this period secretions of a 
peculiar nature are produced. 

When the constituent removed from the blood is 
a product of an unnatural manner of living, or when 
its formation takes place only at a certain age, the 
susceptibility of contagion ceases upon its disap- 
pearance. 

The effects of vaccine matter indicate, that an 
accidental constituent of the blood is destroyed by 
a peculiar process of decomposition, which does not 
affect the other constituents of the circulating fluid. 

If the manner in which the precipitated yeast of 
Bavarian beer acts (page 350) be called to mind, 
the modus operandi of vaccine lymph can scarcely 
be matter of doubt. 

Both the kind of yeast here referred to and the 
ordinary ferment are formed from gluten, just as the 
vaccine virus and the matter of smallpox are pro- 
duced from the blood. Ordinary yeast and the virus 
of human smallpox, howevfer, effect a violent tumul- 
tuous transformation, the former in vegetable juices, 
the latter in blood, in both of which fluids respec- 
tively their constituents are contained, and they are 
reproduced from these fluids with all their character- 
istic properties. The precipitated yeast of Bavarian 
beer on the other hand acts entirely upon the sugar 
of the fermenting liquid and occasions a very pro- 
tracted decomposition of it, in which the gluten 
which is also present takes no part. But the air 
exercises an influence upon the latter substance, and 
causes it to assume a new form and nature, in con- 
sequence of which this kind of yeast also is repro- 
duced. 

The action of the virus of cow-pox is analogous 
to that of the low yeast ; it communicates its own 



406 POISONS, CONTAGIONS, MIASMS, 

state of decomposition to a matter in the blood, and 
from a second matter is itself regenerated, but by a 
totally different mode of decomposition; the product 
possesses the mild form, and all the properties of 
the lymph of cow-pox. 

The susceptibility of infection by the virus of 
human smallpox must cease after vaccination, for 
the substance to the presence of which this suscep- 
tibility is owing has been removed from the body by 
a peculiar process of decomposition artificially ex- 
cited. But this substance may be again generated 
in the same individual, so that he may again become 
liable to contagion, and a second or a third vaccina- 
tion will again remove the peculiar substance from 
the system. 

Chemical actions are propagated in no organs so 
easily as in the lungs, and it is well known that dis- 
eases of the lungs are above all others frequent and 
dangerous. 

If it is assumed, that chemical action and the vital 
principle mutually balance each other in the blood, it 
must further be supposed that the chemical powers 
will have a certain degree of preponderance in the 
lungs, where the air and blood are in immediate 
contact; for these organs are fitted by nature to 
favor chemical action ; they offer no resistance to the 
changes experienced by the venous blood. 

The contact of air with venous blood is limited to 
a very short period of time by the motion of the 
heart, and any change beyond a determinate point 
is, in a certain degree, prevented by the rapid re- 
moval of the blood which has become arterialized. 
Any disturbance in the functions of the heart, and 
any chemical action from without, even though weak, 
occasions a change" in the process of respiration. 
Solid substances, also, such as dust from vegetable, 
animal, or inorganic bodies, act in the same way as 
they do in a saturated solution of a salt in the act 
of crystallization, that is, they occasion a deposition 



THEIR MODE OF ACTION. 407 

of solid matters from the blood, by which the action 
of the air upon the latter is altered or prevented. 

When gaseous and decomposing substances, or 
those which exercise a chemical action, such as sul- 
phuretted hydrogen and carbonic acid, obtain access 
to the lungs, they meet with less resistance in this 
organ than in any other. The chemical process of 
slow combustion in the lungs is accelerated by all 
substances in a state of decay or putrefaction, by 
ammonia and alkalies; but it is retarded by empy- 
reumatic substances, volatile oils, and acids. Sulphu- 
retted hydrogen produces immediate decomposition 
of the blood, and sulphurous acid combines with the 
substance of the tissues, the cells, and membranes. 

When the process of respiration is modified by 
contact with a matter in the progress of decay, when 
this matter communicates the state of decomposition, 
of which it is the subject, to the blood, disease is 
produced. 

If the matter undergoing decomposition is the 
product of a disease, it is called contagion ; but if 
it is a product of the decay or putrefaction of ani- 
mal and vegetable substances, or if it acts by its 
chemical properties, (not by the state in which it is,) 
and therefore enters into combination with parts of 
the body, or causes their decomposition, it is termed 
miasm. 

Gaseous contagious matter is a miasm emitted 
from blood, and capable of generating itself again in 
blood. 

But miasm properly so called, causes disease with- 
out being itself reproduced. 

All the observations hitherto made upon gaseous 
contagious matters prove, that they also are sub- 
stances in a state of decomposition. When vessels 
filled with ice are placed in air impregnated with 
gaseous contagious matter, their outer surfaces be- 
come covered with water containing a certain quan- 
tity of this matter in solution. This water soon 
becomes turbid, and in common language putrefies, 



408 POISONS, CONTAGIONS, MIASIMS. 

or, to describe the change more correctly, the state 
of decomposition of the dissolved contagious matter 
is completed in the water. 

All gases emitted from putrefying animal and 
vegetable substances in processes of disease, gener- 
ally possess a peculiar nauseous offensive smell, a 
circumstance which, in most cases, proves the pres- 
ence of a body in a state of decomposition. Smell 
itself may in many cases be considered as a reaction 
of the nerves of smell, or as a resistance offered by 
the vital powers to chemical action. 

Many metals emit a peculiar odor when rubbed, 
but this is the case with none of the precious metals, 
— those which suffer no change when exposed to air 
and moisture. Arsenic, phosphorus, musk, the oils 
of linseed, lemons, turpentine, rue, and peppermint, 
possess an odor only when they are in the act of 
eremacausis (oxidation at common temperatures). 

The odor of gaseous contagious matters is owing 
to the same cause; but it is also generally accom- 
panied by ammonia, which may be considered in 
many cases as the means through which the con- 
tagious matter receives a gaseous form, just as it is 
the means of causing the smell of innumerable sub- 
stances of little volatility, and of many which have 
no odor. (Robiquet.)* 

Ammonia is very generally produced in cases of 
disease; it is always emitted in those in which con- 
tagion is generated, and is an invariable product of 
the decomposition of animal matter. The presence 
of ammonia in the air of chambers in which diseased 
patients lie, particularly of those afflicted with a 
contagious disease, may be readily detected ; for the 
moisture condensed by ice in the manner just de- 
scribed, produces a white precipitate in a solution 
of corrosive sublimate, just as a solution of ammonia 
does. The ammoniacal salts also, which are obtained 
by the evaporation of rain water after an acid has 

* Ann. de Chim. et de Pliys. XV. 27. 



THEIK MODE OF ACTION. 409 

been added, when treated with lime so as to set free 
their ammonia, emit an odor most closely resembling 
that of corpses, or the peculiar smell of dunghills. 

By evaporating acids in air containing gaseous 
contagions, the ammonia is neutralized, and we thus 
prevent further decomposition, and destroy the pow- 
er of the contagion, that is, its state of chemical 
change. Muriatic and acetic acids, and in several 
cases nitric acid, are to be preferred for this purpose 
before all others. Chlorine also is a substance which 
destroys ammonia and organic bodies with much 
facility; but it exerts such an injurious and prejudi- 
cial influence upon the lungs, that it may be classed 
amongst the most poisonous bodies known, and 
should never be employed in places in which men 
breathe. 

Carbonic acid and sulphuretted hydrogen, which 
are frequently evolved from the earth in cellars, 
mines, wells, sewers, and other places, are amongst 
the most pernicious miasms. The former may be re- 
moved from the air by alkalies; the latter, by burn- 
ing sulphur (sulphurous acid), or by the evaporation 
of nitric acid. 

The characters of many organic compounds are 
well worthy of the attention and study both of phys- 
iologists and pathologists, more especially in relation 
to the mode of action of medicines and poisons. 

Several of such compounds are known, which to 
all appearance are quite indifferent substances, and 
yet cannot be brought into contact with one another 
in water without suffering a complete transformation. 
All substances which thus suffer a mutual decompo- 
sition, possess complex atoms ; they belong to the 
highest order of chemical compounds. For example, 
amygdalin, a constituent of bitter almonds, is a per- 
fectly neutral body, of a slightly bitter taste, and 
very easily soluble in water. But when it is intro- 
duced into a watery solution of synaptas, (a constit- 
uent of sweet almonds,) it disappears completely 
without the disengagement of any gas, and the wa- 
35 



410 POISONS, CONTAGIONS, MIASMS. 

ter IS found to contain free hydrocyanic acid, hydru- 
ret of benzule (oil of bitter almonds), a peculiar acid 
and sugar, all substances of which merelj'- the ele- 
ments existed in the amygdalin. The same decom- 
position is effected when bitter almonds, which con- 
tain the same white matter as the sweet, are rubbed 
into a powder and moistened with water. Hence it 
happens that bitter almonds pounded and digested 
in alcohol, yield no oil of bitter almonds containing 
hydrocyanic acid, by distillation with water ; for the 
substance which occasions the formation of those 
volatile substances, is dissolved by alcohol without 
change, and is therefore extracted from the pounded 
almonds. Pounded bitter almonds contain no amyg- 
dalin, also, after having been moistened with water, 
for that substance is completely decomposed when 
they are thus treated. 

No volatile compounds can be detected by their 
smell in the seeds of the Sinapis alba and ^S. nigra. 
A fixed oil of a mild taste is obtained from them by 
pressure, but no trace of a volatile substance. If, 
however, the seeds are rubbed to a fine powder, and 
subjected to distillation with water, a volatile oil of 
a very pungent taste and smell passes over along 
with the steam. But if, on the contrary, the seeds 
are treated with alcohol previously to their distilla- 
tion with water, the residue does not yield a volatile 
oil. The alcohol contains a crystalline body called 
sinapin, and several other bodies. These do not 
possess the characteristic pungency of the oil, but it 
is by the contact of them with water, and with the 
albuminous constituents of the seeds, that the vola- 
tile oil is formed. 

Thus bodies regarded as absolutely indifferent in 
inorganic chemistry, on account of their possessing 
no prominent chemical characters, when placed in 
contact with one another, mutually decompose each 
other. Their constituents arrange themselves in a 
peculiar manner, so as to form new combinations ; a 
complex atom dividing into two or more atoms of 



THEIR MODE OF ACTION. 411 

less complex constitution, in consequence of a mere 
disturbance in the attraction of their elements. 

The white constituents of the almonds and mus- 
tard which resemble coagulated albumen, must be in 
a peculiar state in order to exert their action upon 
amygdalin, and upon those constituents of mustard 
from which the volatile pungent oil is produced. If 
almonds, after being blanched and pounded, are 
thrown into boiling water, or treated with hot alco- 
hol, with mineral acids, or with salts of mercury, 
their power to effect a decomposition in amygdalin 
is completely destroyed. Synaptas is an azotized 
body which cannot be preserved when dissolved in. 
water. Its solution becomes rapidly turbid, deposits 
a white precipitate, and acquires the offensive smell 
of putrefying bodies. 

It is exceedingly probable, that the peculiar state 
of transposition into which the elements of synaptas 
are thrown when dissolved in water, may be the 
cause of the decomposition of amygdalin, and forma- 
tion of the new products arising from it. The action 
of synaptas in this respect is very similar to that of 
rennet upon sugar. 

Malt, and the germinating seeds of corn in gener- 
al, contain a substance called diastase, which is 
formed from the gluten contained in them, and can- 
not be brought in contact with starch and water, 
without effecting a change in the starch. 

When bruised malt is strewed upon warm starch 
made into a paste with water, the paste after a few 
minutes becomes quite liquid, and the water is found 
to contain, in place of starch, a substance in many 
respects similar to gum. But when more malt is 
added and the heat longer continued, the liquid ac- 
quires a sweet taste, and all the starch is found to 
be converted into sugar of grapes. 

The elements of diastase have at the same time 
arranged themselves into new combinations. 

The conversion of the starch contained in food in- 
to sugar of grapes in diabetes indicates, that amongst 



412 POISONS, CONTAGIONS, MIASMS. 

the constituents of some one organ of the body, a 
substance or substances exist in a state of chemical 
action, to which the vital principle of the diseased 
organ opposes no resistance. The component parts 
of the organ must suffer changes simultaneously with 
the starch, so that the more starch is furnished to it, 
the more energetic and intense the disease must 
become; while if only food which is incapable of 
suffering such transformations from the same cause 
is supplied, and the vital energy is strengthened by 
stimulant remedies and strong nourishment, the 
chemical action may finally be subdued, or in other 
words, the disease cured. 

The conversion of starch into sugar may also be 
effected by pure gluten, and by dilute mineral acids. 

From all the preceding facts, we see that very va- 
rious transpositions, and changes of composition and 
properties, may be produced in complex organic 
molecules, by every cause which occasions a disturb- 
ance in the attraction of their elements. 

When moist copper is exposed to air containing 
carbonic acid, the contact of this acid increases the 
affinity of the metal for the oxygen of the air in so 
great a degree that they combine, and the surface of 
the copper becomes covered with green carbonate 
of copper. Two bodies, which possess the power 
of combining together, assume, however, opposite 
electric conditions at the moment at which they come 
in contact. 

When copper is placed in contact with iron, a pe- 
culiar electric condition is excited, in consequence 
of which the property of the copper to unite with 
oxygen is destroyed, and the metal remains quite 
bright. 

When formate of ammonia is exposed to a temper- 
ature of 388° F. (180° C.) the intensity and direction 
of the chemical force undergo a change, and the 
conditions under which the elements of this com- 
pound are enabled to remain in the same form cease 
to be present. The elements, therefore, arrange 



THEIR MODE OF ACTION. 413 

themselves in a new form ; hydrocyanic acid and 
water being the results of the change. 

Mechanical motion, friction, or agitation, is suffi- 
cient to cause a new disposition of the constituents 
of fulminating silver and mercury, that is, to effect 
another arrangement of their elements, in conse- 
quence of which, new compounds are formed. 

We know that electricity and heat possess a de- 
cided influence upon the exercise of chemical affinity ; 
and that the attractions of substances for one anoth- 
er are subordinate to numerous causes which change 
the condition of these substances, by altering the 
direction of their attractions. In the same manner, 
therefore, the exercise of chemical powers in the 
living organism is dependent upon the vital principle. 

The power of elements to unite together, and to 
form peculiar compounds, which are generated in an- 
imals and vegetables, is chemical affinity ; but the 
cause by which they are prevented from arranging 
themselves according to the degrees of their natural 
attractions, — the cause, therefore, by which they are 
made to assume their peculiar order and form in the 
body, — is the vital principle. 

After the removal of the cause which forced their 
union, — that is, after the extinction of life, — most 
organic atoms retain their condition, form, and na- 
ture, only by a vis inertim; for a great law of nature 
proves, that matter does not possess the power of 
spontaneous action. A body in motion loses its mo- 
tion only when a resistance is opposed to it ; and a 
body at rest cannot be put in motion, or into any 
action whatever, without the operation of some ex- 
terior cause. 

The same numerous causes which are opposed to 
the formation of complex organic molecules, under 
ordinary circumstances, occasion their decomposition 
and transformations when the only antagonist power, 
the vital principle, no longer counteracts the influ- 
ence of those causes. Contact with air and the most 
feeble chemical action now effect changes in the com- 
35* 



414 POISONS, CONTAGIONS, MIASMS. 

plex molecules ; even the presence of any body the 
particles of which are undergoing motion or trans- 
position, is often sufficient to destroy their state of 
rest, and to disturb the statical equilibrium in the 
attractions of their constituent elements. An imme- 
diate consequence of this is, that they arrange them- 
selves according to the different degrees of their 
mutual attractions, and that new compounds are 
formed in which chemical affinity has the ascendancy, 
and opposes any further change, while the conditions 
under which these compounds were formed remain 
unaltered. 



APPENDIX TO PAET 11. 



ANTIDOTE TO ARSENIC. 

The following is from a letter of Samuel L. Dana, M. D., 
of Lowell, to Dr. Bartlett, published in the "Boston Daily 
Advertiser." August 3d, I84'2. 

"According to the experiments of M. Guibourt, white ox- 
ide of arsenic, (or white arsenic) digested with hydrated 
peroxide of iron, forms a compound, whose proportions 
differ from that of arsenite of iron, by containing a larger 
portion of iron. It is this salt, which forms in the stomach, 
when peroxide of iron is administered as an antidote to 
arsenic. It contains 3| times as much iron as arsenic. It 
is perfectly insoluble and innocuous. Three things are 
essential to the action of this antidote. 

" 1st. Perfect freedom from protoxide of iron. 

"2d. Perfect freedom from free alkali, or alkali com- 
bined with the oxide of iron. 

"3d. It must be freshly prepared without drying. 

" 1st. If the antidote contains protoxide of iron, then 
that combines with the arsenic and forms a compound 
which, though of sparing solubility, is yet poisonous and 
prevents the ulterior good action of the peroxide of iron. 
A mixture of prot and peroxides of iron is no antidote to 
arsenic. 

" 2d. If carbonate of potash is used to precipitate a solu- 
tion of persalt of iron, a portion falls, combined with alka- 
li. Hence Berzelius recommends bicarbonate of potash, 
cold, to be used for this purpose. The effect of alkali, 
free, or thus combined with peroxide of iron, will be, to 
form soluble poisonous arsenites as above noticed. 

"3d. The effect depends on the antidote being freshly 
prepared. I would therefore, in order to insure the 2d 
and 3d conditions, recommend the solution of pernitrate of 
iron to be taken dilute, followed by aq. am. and wet by a 



416 



TABLES. 



little vinegar or tartaric acid, or cream of tartar ; remedies 
always at hand. 

"To insure perfect freedom from protoxide of iron, 
I would always pass a current of chlorine, through the 
solution of prepared nitrate of iron, before that is con- 
sidered as fit, to be kept on hand, for the ready formatioa 
of hydrated peroxide of iron. 



TABLES: 



SHOWING THE PROPORTION BETWEEN THE HESSIAN AND 
ENGLISH STANDARD OF WEIGHTS AND MEASURES. 



In general all the weights and measures employed in this 
edition are those of the English standard. In a few cases 
only, the Hessian weights and measures have been re- 
tained. In these the numbers do not represent absolute 
quantites, but are merely intended to denote a proportion 
to other numbers. This has been done to avoid any un- 
necessary intricacy in the calculations, and to present 
whole numbers to the reader, without distracting his at- 
tention by decimal parts. For those, however, who wish 
to be acquainted with the exact English quantities, a table 
is here given below. 

1 lb. English is equal to 0-90719 lb. Hessian ; hence, 
about one-tenth less than the latter. 



1 lb. Hessan is equal to 


1102 lb. 


English 


2 lbs. Hessian are equal to 


2-204 


lbs 


" 


3 . . . 


. 3-306 




(( 


4 




4-409 




(( 


5 




. 5-511 




<( 


6 




6-612 




(( 


7 




. 7716 




<( 


8 




8-818 




« 


9 




. 9-!t2 




(( 


10 




11 02 




<i 


20 




. 2204 




u 


30 




33 06 




<( 


40 




. 44-09 




<( 


50 




55-11 




« 


60 




. 66-12 




u 


70 




77 16 




(C 


80 




. 88 18 




« 


90 




99-29 




(( 


100 




110-2 




(( 


200 




220-4 




(( 



TABLES. 



417 



300 lbs. Hessian are equal to 330-6 lbs. English. 

400 . . . 4400 " 

500 ... 5511 " 

600 . . . 661-2 " 

700 ... 771-6 " 

800 . . . 881-8 " 

900 ... 9920 " 



1000 



11U2-0 



SQUARE FEET. 



The Hessian acre is equal to 40,000 Hessian square 
feet, or 26,911 English square feet ; 1 English square foot 
being equal to 1'4864 Hessian. The following is a Table 
to save the trouble of calculation. The table is only stated 
to the figure 10, but by removing the decimal point one or 
two figures, the whole series given in the case of the 
pounds will also be obtained. 

1 Square Foot Hessian is equal to 0G73 Square Foot English. 

2 feet . . . . 1-345 " 



3 
4 
5 
6 

7 

8 

9 

10 



2-018 
2-691 
3-363 
4-036 
4-709 
5-382 
6-054 
6-727 



feet 



CUBIC FEET. 



One English cubic foot contains 1 '8 121 8 of a Hessian 
cubic foot ; the Hessian and English cubic inch may be 
considered as equal, one English cubic inch containing 
r0487 15 Hessian cubic inch. 

1 cubic foot Hessian is equal to 0-551 cubic foot English. 

2 feet . . . . 1-103 « 

3 ... 1-655 " 

4 . . . . 2207 feet. 

5 ... 27.59 «' 

6 . . . . 3-311 " 

7 ... 3-863 « 

8 . . . . 4415 " 

9 ... 4-966 " 
10 ... . 5518 " 



418 



TABLES. 



TABLE OF THE CORKESPONDING DEGREES ON THE SCALES OF 
FAHRENHEIT, REAUMUR, AND CELSIUS, OR CENTIGRADE. 



1 


3 


G 


03 


Pi 


c 
O 


fa 


VI) 




212 


80 


100 


149 


52 


65 


50 


8 


10 


203 


76 


95 


140 


48 


60 


41 


4 


5 


194 


72 


90 


131 


44 


55 


32 








185 


68 


85 


122 


40 


50 


23 


— 4 


— 5 


176 


64 


80 


113 


36 


45 


14 


— 8 


— 10 


167 


60 


75 


104 


32 


40 


5 


— 12 


— 15 


158 


56 


70 


95 


28 


35 


4 


— 16 


— 20 








86 


24 


30 


— 13» 


— 20 


— 25 








77 


20 


25 


— 22 


-24 


— 30 








68 


16 


20 


— 31 


-28 


— 35 








59 


12 


15 


— 40 


— 32 


— 40 



• — Denotes below the cipher on Fahrenheit's scale. 



INDEX. 



ACI 

.Abnormal, meaning of the term, 

140. 
Absorption, by roots, 107. 

Of salts, IIG. 
Acetone, 306. 
Acid, acetic, emitted by plants, 150. 

compound atom of, 301. 

transformation of, 306. 

formation of, 329-334. 

Apocrenic, 31. 

Boracic, 122. 

Carbonic, 24-70. 

contained in the atmo- 
sphere, 28. 

decomposed by plants, 

43. 

from respiration, 44. 

from springs, 29. 

why necessary to 

plants, 105. 

Crenic, 31. 

Cyanic, transformation of, 310. 

Cyanuric, 70. 

Formic, 71, 86, 290. 

Hippuric, 97. 

Humic, 31. 

properties of, 34. 

Hydrocyanic, 70, 290. 

Hydromellonic, 70. 

Hypochlorous, 293. 

Kinic, 114. 

Kinovic, 301. 

Lactic, 190. 

production of, 321. 

Meconic, 115. 

Melanic, 326. 

Mellitic, 363. 

Nitric, source of, 88. 

Oxalic, 70. 

Phosphoric, in ashes of plants, 
155. 

Rocellic, in plants, 108. 



ALK 

Acid, succinic, 363. 

Sulphuric, action of, on soils, 
208, 248. 

Tartaric, in grapes, 108. 
Acids, action of upon sugar, 303. 

Arrest decay, 361 

Capacity for saturation, 108. 

Organic, in plants, 27, 107. 

when formed, 51. 

Acre, Hessian, 36. 
Adipocire, 88. 
Affinity, action of, 71. 

Chemical, examples of, 292. 

Weak, example of, 293. 
Agave Americana, absorbs oxygen, 

51. 
Ao-riculture, in China, 193. 

Object of, 100, 145, 172. 

how attained, 146. 

Its importance, 143. 

A principle in, 187. 
Air, access of, favored, 65. 

Ammonia in, 29, 91. 

Carbonic acid in, 41. 

Effect of upon juices, 330. 

on soils, 167. 

Expired in phthisis, 73. 

Improved by plants, 47. 

Necessary to plants, 130. 
Albumen, 96, contains nitrogen, 27. 
Alcohol, effect of heat on, 306. 

Exhaled, 72. 

Products of its oxidation, 327. 

From sugar, 313. 
Aldehyde, 327. 
Alkalies, 69, from granitic soils, 117. 

Presence of, indicated, 215. 

Promote decay of wood, 361. 

Quantity in aluminous minerals, 
148. 
Alkaline Bases, in plants, on what 
their existence depends, 112. 



ANA 



420 



AZO 



Mkaline Bases, salts contained in 
fertile soils, 153. 

Salts in plants, sources of, 151. 
Jlllantoin, 70. 
Mloxan, 352. 
Alloxantin, 352. 
Mumina, in fertile soils, 147. 

Its influence on vegetation, 147. 

Mistaken in ashes, 148. 
Amber, origin of, 363. 
Jlmmelin, 70. 

Ammonia, 70, 86, carbonate of, from 
urine, 191. 

how fixed, 191. 

Cause of nitrification, 338. 

Changes colors, 87. 

Condensed by charcoal, 104. 

Conversion of, into nitric acid, 
338. 

Decomposition of by plants, 2G6. 

Early existence of, 123. 

Fixed by gypsum, 191. 

From animals, 174. 

Contained in beet-root, &c., 93. 

maple juice, 94. 

stables, &c., 192. 

Furnishes nitrogen, 104. 

Loss from evaporation, 99. 

prevented, 280. 

Produced by animal organism, 
123. 

Product of decay, 88. 

disease, 408. 

Properties of, 88. 

Quantity absorbed by charcoal, 
104. 

by decayed 

wood, 104. 

In rain water, 90. 

How detected, 91. 

Separated from soils by rain, 104. 

In snow water, 91. 

Solubility of, 89. 

Sulphate of, 281. 

Transformation of, 86. 
Jlmmoiiidcal Liquor, 283. 
Jlmylin, its effect, 74. 
Analysis of decayed wood, 359. 

Of fire-damp, 372. 

Of fishes, 177. 

Of horse-dung, 177. 

Of peat, 185. 

Of guano, 201. 

Of lentils, 159. 

Of oak-wood, 358. 

Of night-soil, 179. 

Of salt water, 124. 



Analysis, of soils, 217, 245. 

Of wood coal, 367, 368. 
Animal food, preservation of, 330. 

Life, connexion of, with plants, 
22. 

Bodies, products of decay, 88. 

complex, 302. 

Animals, excrements of, 189. 

Nutriment of, 22. 
Annual plants, how nourished, 135. 
Anlhoxanthum Odoratuvi, acid in, 

97. 
Anthracite, 373. 
Antidotes to Poisons, 381. 
Apatite, 156. 
Apotheme, 31. 
Arable Land, 146. 
Aromatics, their influence on fer- 
mentation, 343. 
Argillaceous Earth, its origin, 147. 
Arragonite, transformation of, 298. 
Arroio Root, 140. 
Arsenious Arid, action of, 381. 
Artificial Manure, 199, 287. 
Ashes, as manure, 182, 198. 

Comparative value of, 182. 

Of fir-wood, 111. 

Of pine trees, 110. 

Of plants, origin of salt in, 125. 

Importance of examination of, 
112. 

Of wheat, 158. 

used as a manure, 213. 

Of bones, 183. 

Of peat, 18.5. 

Of coals, 198. 

Phosphate of lime in, 183. 
Assimilation, of carbon, 30. 

Of carbonic acid, and ammonia, 
131. 

Of hydrogen, 80 - 84. 

Of nitrogen, 85-105. 

Its power, 140. 
Atmosphere, ammonia in, 29, 92. 

Composition of, 27. 

How maintained, 44. 

Composition is invariable, 40. 

Carbonic acid in the, 28-41. 

Motion of, 46. 

Oxygen in, 26. 
Atoms, motions of, 297. 

Permanence in position of, 297. 
j?/?<raciion, powerful, overcome, 309. 
Azores, glairin found there, 34. 

Carbonic acid at the, 79. 

Silica in hot springs of, 170. 
Azote, 25. 



BOT 



421 



CAR 



j'lzotized matter in juices of plants, 
137. 
Substances, combustion of, 334. 
Azulmin, 70. 

Bamboo, silica in, 171. 

Bark of trees, products in, 49. 

Barilla, 118. 

Barley, analysis of, 155. 

Barruel, his experiments on the 

blood, 403. 
Base, what, (>!», 106. 
Bases, alkaline, in plants, on what 
their existence depends, 112. 

Organic, 27. 

Oxygen contained in, 106. 

In plants, 108. 

Substitution of, 109. 
Beans, alkalies in, 159. 

Nutritive power of, 159. 
Becquerel, experiments of, 150. 
Beech, ashes of, 182. 
Beer, 347-257. 

Bavarian, 343. 

Varieties of, 347. 
Beet-root sugar, 38. 

Ammonia from, 93. 

From sandy soils, 140. 
Belgium, soils of, 241. 
Benignant Disease, 402. 
Benzoic acid, formed, 97. 
Berzeliiis, humic extract of, 34. 

His analysis of bones, 158. 
Birch Tree, ammonia from, 94. 
Bischoff, estimate of carbonic acid, 

&c., 29. 
Blake, on nitrate of aoda, 270. 
Bleaching Salts, 141. 
Blood, its office, 135. 

Action of chemical agents upon, 
396. 

Its feeble resistance to exterior 
influences, 3il6. 

Organic salts in, 375. 

Its character, 386. 
Blossoms, when produced, 68. 

Increased, 132. 

Removal of, from potatoes, 134. 
Bones, dust of, 183. 

Durability of, 204. 

Gelatine in, 203. 

Use in composts, 212. 

Composition of, 157, 158. 
Bouquet of wines, 342. 
Boracic Acid, 122. 
Botanists, neglect of chemistry by, 
55. 

36 



Bran, use of, 185. 
Brandxj, from corn, 342. 

Oil of, 342. 
Brazil, wheat in, 153. 
Bread, from wood, 133. 
Brown Coal, 185. 
Buckwheat, ashes of, 159. 
Bulbs, how nourished, 76. 

Calcareous Spar, 298. 

Calcium, fluoride of, 157. 

Chloride of, 192. 
Calculous Disorders, 74. 
Calico Printing, use of cow-dung 
in, 186. 

Use of phosphate of soda in, 286. 

Substitute for, 186, 286. 
Caoutchouc, in plants, 78. 
Carbon, 24. 

Afforded to the soil by plants, 76. 

Assimilation of, 30 -63. 

Combination of, with oxygen, 24. 

Of decaying substances seldom 
affected by oxygen, 360. 

Derived from air, 44. 

In decaying wood, 360. 

In decaying woody fibre, 361. 

In sea- water, 45. 

Oxide of, formed, 305. 

Quantity m grain, 38. 

in land, 39. 

in straw, 38. 

given off by man, 41. 

Restored to the soil, 76. 

Received by leaves, 43. 

Its affinity for oxygen, 328. 
Carbonate of ammonia decomposed 
by gypsum, 100. 

Of soda, 207. 

Of lime in caverns and vaults, 
128. 
'Carbonic acid, 70, in the atmo- 
sphere, 28. 

In St Michaels, 79. 

Changes in leaves, 142. 

Decomposed by plants, 43. 
Emission of, at night, 49. 

Evaporation of, 56. 

Evolution from decaying bodies, 
328. 

From decaying plants, 84. 

excrements, 99. 

humus, 65. 

respiration, 72. 

springs, 29, 85. 

woody fibre, 64. 

Quantity extracted from air, 45. 



CON 



422 



DAU 



Carbonic J}cid, influence of light 
on its decomposition, 53. 

Increase of, prevented, 42. 
Carbon of Plants, source of, 260 - 

2d5. 
Carburetled hydrogen with coal, 

372. 
Caverns, stalactites in, 127, 
Charcoal, what, 24. 

Condenses ammonia, 104. 

Experiments of Lucas on, 249. 

May replace humus, 78. 

Theory of its action, 78. 

Promotes growth of plants, 240. 
C/<e^ms/brrf, analysis of soil of, 246. 
Chemical effects of light, 141. 

Forces can replace the vital prin- 
ciple, 75. 

Processes in nutrition of vege- 
.tables, 22. 

Transformations, 69, 289. 
Chemistrij, definition of, 21 . 

Organic, what is, 22. 

Neglected by botanists, 55 ; and 
physiologists, 56. 
China, its agriculture, 193. 

Collection and use of manure 
in, 1!)3. 
Chlorine gas, 141 : effect of, 101. 
Chloride of calcium, 192. 

Of nitrogen, 2; '3. 

Of potassium, its effect, 116. 

Of sodium, its volatility, 123. 
Clay, burned, advantages of, as a 

manure, 102. 
Clays, potash in, 148. 
Clay slate, 157. 
Coal, formation of, 369. 

Ammoniacal liquor from, 2U5. 

Inflammable gases from, 372. 

Origin of substances in, 363. 

Of humus, 30, 129. 

Wood or brown, 185. 
Colors of flowers, 96. 
Combustion at low temperatures, 
327. 

Of decayed wood, 362. 

Induction of, 332. 

Removes oxygen, 42. 

Spontaneous, 324. 
Compost manure, 1 18, 212, 279. 
Concretions from horses. 156. 
Constituents of plants, 24. 
Consumption, 73. 

Contagion, reproduction of, on 
what dependent, 389. 



Contagion, susceptibility to, how 

occasioned, 401. 
Contagions, how produced, 389. 

Propagation of, 398. 
Contagious matters, action of, 394, 
399, 413. 

Their effects explained, 390. 

Life in, disproved, 392. 

Reproduction of, 392. 
Copper alloy, its action, on sulphu- 
ric acid, 2;i2. 
Corn, how cultivated in Italy, 152 

Phosphate of magnesia in, 156. 

Effect of carbonic acid on, 7!). 
Corn brandy, 342. 
Corrosive sublimate, action of, 381. 
Cow, excrements of the, 120, 176, 
178. 

Variable in value, 179. 

Urine of the, 177; rich in potash, 
119. 
Coio pox, action of virus of, 405. 
Crops, rotation of, 161. 

Favorable effects of, 162. 

Principles regulating, 174, 275. 
Cubic nitre, 270. 
Cultivation, its benefits, 47. 

Different methods of, 144. 

Object of, 14.5. 
Culture, art of, 126. 

Of plants, principles of the, 144. 
Cyanic acid, transformation of, 311. 
Cyanogen, combustion of, 335. 

A compound base, 70. 

Transformation of, 311. 
Cyanuric acid, 70. 

Dana, Dr. S. L , on geine, 31. 

On phosphate of lime, 182. 

On ammonia, 259. 

On phosphate of soda in calico 
printing, 286. 
Daniel's manure, 287. 
Darioin, on nitrate of soda, 270. 
Daubeny, experiments of, 105. 

On forest trees, 164. 

On nutritive qualities of plants, 
265. 

On source of carbon, 285. 

On source of carbon of plants, 
260. 

On source of hydrogen of plants, 
203. 

Carbon of, 260. 

Experiments at Oxford, 257. 

Experiments on his farm, 273. 

Source of hydrogen, 263. 



EXC 



423 



FRU 



Davis, his account of Chinese 

manure, 193. 
Death from nutritious substances, 
59. 

The source of life, 105. 
DecatidoUe, his theory of excre- 
tion, 163. 

Difference of his views and 
those of Macaire-Princep, 1G7. 
Decay, '292. 

A source of ammonia, 88. 

Of wood, 301. 

Of plants restores oxygen, 84. 
and putrefaction, 291. 
Decompositiun. 68, 289. 

Organic, chemical, 291. 
Dextrine, 56, 57. 
Diamond, its origin, 363. 
Diastase, 136. 

Contains nitrogen, 136. 
Disease, how excited, 386. 
Dog, excrement of the, 175. 
Dung hills, liquid from, 191. 

Reservoirs, 191. 

Substitute, 187. 

Ebony wood, oxygen and hy- 
drogen in, 53. 
Effete matters separated, 68. 
Eifel, springs evolve carbonic acid, 

29. 
Elements of plants, 24 

Not generated by organs, 59. 
Elphinstone, Sir Howard, on soda- 
ash as a manure, 207. 
England, analysis of soils in, 242. 
Equilihrmm of attractions dis- 
turbed, 298. 
EquisetacetB contain silica, 171. 
Eremacausis, ()3, 299. 

Analogous to putrefaction, 328. 

Arrested, 323. 

Definition of, 299. 

Necessary to nitrification, 335. 

Of bodies containing nitrogen, 

334. 
Of bodies destitute of nitrogen, 
329. 
Ether, cenanthic, 344. 
Etiolation, 46. 
Eudiometer, 90. 
Excrementitious matter, production 

of, illustrated, 71. 
Excrement, animal, its chemical 
nature, 175. 
Of the dog, cow, &,c., 175. 
Influence of, as manure, 180. 



Excrements of plants, 163. 

Conversion of, into humus, 35. 

Of man, amount of, 195. 

Value of, 189. 

Preservation of, 193. 
Excretion, organs of, 72. 

Of plants, theory of, 163. 
Experiments in physiology, object 
of, 56. 

Of physiologists not satisfactory, 
61. 
Extract of humus, 31. 

Fallow, changes from, 152. 

Crops, 159. 

Time, 159. 
Fattening of animals, 146. 
Faces, analysis of, 179. 
Ferment, 313, 314. 
Fermentation, 299, 300. 

Causes of, 2;i2. 

Of Bavarian beer, 348. 

Of beer, 349. 

Gay-Lussac's experiments inj 
330. 

Of sugar, 313. 

Of vegetable juices, 314. 

Vinous, 338. 

Of wort, 339. 
Fertility of fields, how preserved, 

181. 
Fires, plants on localities of, 154. 
Firs, succeed oaks, 164. 
Firroood, analysis of its ashe.s, 111. 
Fishes, in salt-pans, 121. 

As manure, 259 
Flanders, manure in, 193. 
Fleuhane, 160. 
Flesh, composition of, 177. 

Effect of salt on, 377. 
Flour, bran of, 185. 
Flowers, colors due to ammonia, 96. 
Fluorine, 157; in ancient bones, 

158. 
Foliage, increased, 101. 
Food, effect on products of plants, 
139. 

Of young plants, 131. 

Transformation and assimilation.: 
of, 72. 
Formation of wood, 138. 
Formic acid, 70, 290. 

Theory of its formation, 71 . 

From hydrocyanic acid, 71. 
Fossil resin, origin of, 303. 
Franconia, caverns in, 127. 
Fna7, increased, 132. 



HES 



424 



INO 



Fruit, ripening cf, 83. 

changes attendinff, 

132. ^' 

Fulminating silver, 233. 

GASEOUS substances in the lungs, 

effect of, 407. 
Gasterosteun aculeatus, in salt-pans, 

121. 
Gasioorks, liquor of, 205, 283. 
Gay-Lussac^ his experiments, 330. 
Geine, 31. 

Germany, cultivation in, 181. 
Germination of potatoes, 1 33. 

Of grain, 137. 
Glairin, 34. 
Glass, as a manure, 187. 

Effect ofheat on, 2.97. 
Glue, manure from, 184. 
Gluten, conversion of, into yeast, 
348-3.56. 

Decomposition of, 321. 

Gas from, 339. 
Grain, germination of, 137. 

Manure for, 119. 

Rust in, 220. 
Granitic, soil affords alkalies, 117. 
Grapes, fermentation of, 338. 

Juice of, differences in, 346. 

Potash in, 112. 
Grasses, seeds of, follow man, 121. 

Silica in, 170. 

Valued in Germany, 169. 

Compost for, 118. 
Grauwacke, soil from, 147. 
Growth of plants, conditions for 

the, 144. 
Guano, 95, 199. 

Gypsum, decomposition of, 100, 
280. 

Its influence, 101. 

Use of, 191. 

Theory of, 280. 

Substitutes for, 282. 

Action of, 247, 280. 

Replaced, 248. 

HAILSTONES, 91. 
Hay, carbon in, 38. 

Contains nitrogen, 176. 

silica, 155. 

Analysis of, 38. 
Haystack, effect of lightning upon 

a, 155. 
Hesse, custom in, 213. 
Hessian and English weights and 
measures, 416. 



Hessian acre, 36. 
Hibernating animals, 134. 
Hippuric acid, 97. 
Horse, urine of the, 102 

Concretions in the, 157. 
Horse dung, action of water upon, 
177. 

Analysis of, 173. 
Human faces, analysis of, 179. 
Humate of lime, quantity received 

by plants, 37. 
Humic acid, 31, C5, 90. 

Action of, 129. 

Properties of, 34. 

Is not contained in soils, 90. 

Quantity received by plants, 37. 

Insolubility of, 128. 
Humus, 30, 90. 

Action of, 63. 

Analysis of, 32. 

Erroneous opinions concerning, 
49. 

Extract of, 31. 

Action upon oxygen, 127. 

Coal of, 129. 

Conversion of woody fibre into, 
358. 

How produced, 3iS8. 

Its insolubility, 127. 

Properties of, 34. 

Replaced by charcoal, 78. 

Source of carbonic acid, 65. 

Theory of its action, 65. 

Unnecessary for plants, 33, 77. 
Hungary, soils of, 240. 
Hydrates, 31. 

Hydrocyanic acid, 70, 2.90. 
Hydrogen , assimilation of, 80-82. 

Properties of, 25. 

Excess of in wood accounted 
for, 81. 

Of decayed wood, 359. 

In plants, 203. 

Of plants, source of, 82, 263. 

Peroxide of, 294. 
Hyett, Mr., on nitrate of soda, 206, 
271. 

Ice, bubbles of gas in, 54. 
Indian corn, analysis of, 98. 
Indifferent substances, 27. 
Inflammable air, 25. 
Ingenhouss, his experiments, 49. 
Inorganic compounds, 301. 

Action of, 374. 

In what tliey differ from organic, 
302. 



MAN 



425 



NIT 



Inorganic constituents of plants, 
105, 12(3. 
Compounds, stability of, 301. 
Iodine, 12H. 
Iron, oxide of, attracts ammonia, 

lo:}. 

Irritration of meadows, effect of, 

127, 161). 
Itch insect, 122. 

Jackson, analysis of horse-dung, 
177. 
On peat compost, 258. 
Java, soil of, 244. 
Juices of vegetables, 27. 

Lactic acid, production of, 321. 

Lava, soil from, 149. 

Lead, salts of, compounds with 

organic matter, 383. 
Leaves, absorb carbonic acid, 43. 
Ashes of, contain alkalies, 154 
Cessation of their functions, (JS. 
Change color from absorption of 

oxygen, 68. 
Consequence of the production 

of their green principle, 173. 
Decompose carbonic acid, 142. 
Their office, 135. 
Power of absorbing nutriment, 

how increased, 67. 
Quantity of carbon received by, 

45. 
Contain azotized matter, 188. 
Lentils, analysis of, 159. 
Life, notion of, 392. 
Light, absence of, its effect, 49. 
Chemical effects of, 105, 142. 
Influences decomposition of car- 
bonic acid, 53. 
Lme, phosphate of, 183, 184, 212. 
Limestone, analysis of, 153. 
Liziviation, 182. 

Lucern, phosphate of lime in, 159 
Benefits attending its culture, 
172. 
Lucas, his experiments, 219. 

MaCAIRE-PRINCEP, his experi- 
ments, 161, 256. 
Magnesia, phosphate of, in seeds, 

62. 
Maine, analysis of soil of, 246. 
Mannite. 139. 
Manure,\74,2'^S. 

Animal, yields ammonia, 95, 278. 
Artificial, 204, 212, 287. 

36* 



Mamire, components of, should be 
known, 144. 

Carbonic acid from, 9.>. 

Human, 2rj4. 

Of the Chinese, 193. 

Effect of, 173. 

Bone, 183. 

Daniell's artificial, 287. 
Manuring of vines, 253, 254. 
Maple juice, ammonia from, 94. 

Trees, sugar of, 94. 
Meadoios, irrigation of, 127, 169. 
Medicine, action of, remedies in, 

186. 
Meconic acid, 115. 
Melam, 70. 
Melamin, 70. 
Melitic acid, 363. 
Mellon, 70. 
Merrimack Manuf. Co., first use of 

phosphate of soda by, 286. 
Metallic compounds required by 

plants, (51). 
Metamorphosis, 2:>1. 
Miasm, defined, 407. 
Michaels, St., carbonic acid at, 79. 
Minerals attract ammonia, 103. 
Morbid poisons, 389. 
Motion, its influence on chemical 

forces, 296. 
Mould, vegetable, 363, 

Conversion of woody fibre into, 
364. 

Condenses ammonia, 104. 
Mouldering of bodies, 365. 
Must, fermentation of, 340. 

Naples, soils of, 152, 285. 
Might-soil, 193, 199, 2.59, 284. 
JVde, soil of its vicinity, 168. 
Nitrate of soda as a manure, 206. 

Theory of its formation, 277. 

Of Peru, 270, 277. 

Experimeats with, 271. 
Nitrated wheat, 272. 

Flour, 275. 
Nitric acid, from ammonia, 336. 

Animals, 88. 

How formed, 335. 
Nitrification, 334. 

Condition for, 336. 
Nitrogen from animals, 87. 

Absorption of by plants, 267. 

Account of, 25 

Application of substances con- 
taining it, 99. 

Assimilation of, 85, 97. 



OXY 



426 



PLA 



J\"itrogcn, chloride of, 293. 

Cliaracteristic of, !<J5. 

Compounda of, 25, 27. 

, peculiarity in, 

319. 

In albumen, 27. 

From the atmosphere, 88. 

In plants, 25, 27, 2G5. 

Source of, 28:5, 285. 

Production of, the object of agri- 
culture, Ui). 

Transformation of bodies con- 
taining, 305. 

of bodies not 

containing, 305. 

In rice, 98. 

In solid excrements, 189. 
In urine, 189 
Nutrition, conditions essential to, 
22, 59. 
Inorganic substances required 

in, GO. 
Superfluous, how employed, 07. 
Of young plants, 172. 

Oaks, ashes of, 154. 

E.Ycretions of, 49. 

Dwarf, 6G. 

Followed by firs, 1G4. 
Oak-wood aft'ords humic acid, 35. 

Composition of, 358. 

Mouldered, analysis of, 359. 
Odor of substances, 345. 

Of gaseous contagious matter, 
408. 
CEnanthic ether, 344. 
Ohio, analysis of soils of, 245. 
Orcin, 325. 

Organs of excretion, 72. 
Orgaiiic acids, 26. 

Decomposition of, 295. 

Chemistry, 21, 22. 
Compounds, 82 

Compared with inorganic salts 
in plants, 301. 
Organized bodies do not generate 

substances, Gtt. 
Osmuzome, 317. 
Oxalic acid, 70. 
Oxford, experiments at, 257. 
Oxainide, decomposition of, 391. 
Oxides, metallic, in fir-wood. 111. 
Oxygen, 26. 

Action on alcohol, 327. 

Properties of, 26. 

Absorption of, at night, 51 



Oxygen, absorption by respiration, 
72. 

leaves, 51. 

plants, 49. 

wood, 358. 

Action upon woody fibre, 359. 

Its action in decomposition, 331. 

Emitted by leaves, 43. 

Given to air by land, 80. 

Extracted from air by mould, 364. 

In air, 28. 

Consumption of, 40, 41. 

In water, 82. 

Promotes decay, 130. 

Separated during the formation 
of acids, S'i. 

Is furnished by the decomposi- 
tion of water, 81. 

PJiYEN, his table of composition 

of woods, 264. 
Peat, compost of, 118, 258. 

Analysis of, 18.5. 
Perennial plants, how nourished, 

135. 
Peroxide, what, 295. 
Peroxide of hydrogen, 294. 
Peterson and Schodter, their analy- 
sis of woods, 52. 
Phosphates necessary to plants, 155. 
Phosphate of iron, the probable 
cause of rust, 221. 
In pollen, 182. 
Phosphate of lime in teak wood, 
156. 
In forest soils, 182. 
Phosphoric acid in ashes of plants, 

155. 
Phthisis, remedies in, 73. 
Physiologists, their experiments not 
satisfactory, 62. 
Neglect of chemistry by, 56. 
Pipe-clay, ammonia in, 103. 
Plants absorb oxygen, 50. 
Ashes of, salts in. 1 10. 
Conditions necessary for their 

life, 62. 
Constituents of, 24. 
Decay of, a source of oxygen, 84. 
Decompose carbonic acid, 43. 
Development of, requisites for, 

27, 117,136,143 
Effect of, on rocks, 150. 
Elements of, 24. 
Emit acetic acid, 150. 
Exhalation of carbonic acid 
from, 53. 



PRO 



427 



SAT 



Plants, of a former world, 76. 
Formation of their components, 

b3. 

Functions of, 44. 

Improve tlie air, 47. 

Influence of gases on, 50. 

of shade, 50. 

Inorganic constituents of, 105. 

Life of, connected with that of 
animals, 22. 

Milky-juiced, in barren soils, 78. 

Nutritive qualities of, depend- 
ence on nitrogen, 265. 

Organic acids in, 26, 106. 

salts in, 108. 

Perennial, nourished, 135. 

Products of, vary, 139. 

Size of, proportioned to organs 
of nourishment, 66. 

Sources of their nourishment, 
27. 

Succession of, its advantage, 162. 

Vital processes of, 84. 

Wild, obtain nitrogen from the 
air, 99. 

Yield oxygen, 48. 
Platinum does not decompose nitric 

acid, 292. 
Ploughing, its use, 130. 

Recommended by Cato, 270. 
Poisons generated by disease, 374. 

Inorganic, 374-379. 

Peculiar class of, 384. 

Rendered inert by heat, 389. 
Poisoning, superficial, 379. 

By sausages, 387. 
Pompeii, air from, 41. 

Bones from, 158. 
Potash, action of, upon mould, 364. 

In limestones, 153. 

In grapes, 112. 

Ley of, its effects on excre- 
ments, 99. 

Presence of, in plants, accounted 
for, 148. 

Replaced by soda, 113. 

Required by plants, 62. 

Quantity in soils, 148. 

Si'licate of, in soils, 62. 

Sources of, 148. 
Potatoes, oil of, 341. 

Effect of, as food, 139. 

Analysis of, 114. 

Germination of, 133. 

Produce of, increased, 134. 
Poiidrette, 199. 
Products of transformations, 69. 



Prince, J. D., first to apply phos- 
phate of soda, &,c., 286. 
Purgative effect of salts explained, 

377. 
Pus, globules in, 397. 
Puseij, Mr., on nitrate of soda, 206. 
Putr(faction, 63, 299, 300. 
Of animals, 174. 
Causes of, 292. 
Communicated, 389. 
Source of ammonia, 104. 

carbonic acid, 99. 

Putrefying sausages, death from, 
387; their mode of action, 388. 
Substances, their effect on 
wounds, 389 

alkaline. 397. 

acid, 397. 

Radical, what, 69. 

Rain-water, alkali extracted by, 150. 

Reduction of oxides, 294. 

Reeds and canes require silica, 155. 

Removal of branches, effects of, 132. 

Reservoirs of dung, 191 . 

Respiration, oxygen consumed by, 

41. 
Rhine, soils in its vicinity, 168. 

Wines, 342. 
Rice, analysis of, 98. 
Ripening of fruit, 132. 
Root secretions, 163, 256 
Roots absorb, 107. 

Emit excrementitious matter, 
163. 

Their office, 125. 

Secretions of, 256. 
Rotation of crops, 161, 174. 

Sal ammoniac, as manure, 282. 

Saliculitc of potash, 326. 

Saline plants, 121. 

Salsola kali, 113. 

Salt, volatilization of, 123. 

Salts, absorption of, 116. 

Effect of, on the organism, 375. 

on flesh, 377. 

on the stomach, 377. 

Organic, in plants, 27. 

in the blood, 376. 

Passage of through the lungs, 
376. 
Salt-works, loss in, 1~'4. 
Saltwort, 122. 
Sand, plants in, 78. 
Sandy soil, decay of wood in, 361. 
Saturation, capacity of, 106. 



STA 



428 



TOB 



Sausages, poisonous, 387. 
Saussure, his experiments on air, 42. 

Analysis of pines, 110. 

On the growth of plants, 153. 
Schuhler, his observations on rain, 

90. 
Sea-water, analysis of, 124. 

Contains carbon, 45. 

Contains ammonia, 125. 
Secretions, root, 256. 
Silica, 170, in grasses, 155. 

Solution of, 170. 

In reeds and canes, 155. 
Silicate of ■potash in plants, 62. 

As a manure, 187, 212, 213. 
Siliceous sinter, 170. 
Silver, carbonate of, action on or- 
ganic acids, 295. 

Salts, poisonous effects of, 382. 
Simple bodies, 21. 
Sinapis alba, 410. 
Size of plants proportional to organs 

of nourishment, 66. 
Smell, wliat, 345. 
Snow ID (iter, ammonia in, 91. 
Soda may replace potash, 113. 

Nitrate of, theory of its forma- 
tion, 277. 

Phosphate of, in calico printing, 
286. 
Soda-ash, 207. 

Soils, advantage of loosening, 65, 
130. 

Chemical constituents of, 208. 

Best for meadow-land, 118. 

Carbon restored to, 75. 

Chemical nature of its influence, 
167. 

Constituents of, 208. 

Exhaustion of, 151. 

Ferruginous, improved, 130. 

Fertile, contain phosphoric acid, 
potash, &c., 242, 243. 

Fertile, of Vesuvius, 149. 

From lava, 149. 

Of heaths, 223. 

Imbibe ammonia, 99. 

Improved by crops, 161. 

Impoverished by crops, 161. 

Various kinds of, 208. 
Stagnant water, effect of, 130. 
Stalactites in caverns, 127. 
Starch, ^(); composition of, 83. 

Accumulation of, in plants, 132. 

Development of plants influ- 
enced by, 134. 

Effect of, on malt, 74. 



Starch, vesicles in, 56. 

Product of the life of plants, 49. 

In willows, 133. 
Staunton, Sir G., on Chinese ma- 
nure, 194. 
Straw, analysis of, 38. 
SirM»e, experiments of, 151. 
Substitution of bases, 109. 
S?ibsoil ploughing, 215, 269. 
Succession of crops, 275. 
Succinic acid, 363. 
Sugar, action of alkalies upon, 303. 

acids upon, 303. 

Composiiion of, 313. 

Carbon in sugar, 38. 

Contained in the maple-tree, 93. 

In clerodendion fragrans, &c., 
138. 

Devolopment of plants, influence 
on, 134. 

Fermentation of, 313. 

Formic acid from, 86. 

In beet-roots, 93. 

Metamorphosis of, 313. 

Organic compounds, all form 
sugar, 302. 

Product of the life of plants, 49. 

Transformation of, 304. 

When produced, 67. 
Sulphur, crystallized, dimorphous, 
297. 

In plants, 214. 
Sulphuric Acid, action of, on soils, 

208, 248. 
Sulphurous Acid arrests decay, 360. 
Swamp muck, 185. 
Siceden, soils of, 243. 
Stcine, urine of, 202. 
Sijnaptas, 411. 

Tjibasheer, 171. 

Tables, of Hessian and English 

weights, 416. 
Tannic Acid, 83. , 

Tartaric Acid, 83. 

Converted into sugar, 83. 

In wine, 342. 
Teak Tree, salts found in, 155. 
Teeth, analysis of, 158. * 

Teltoica Parsnep, 66, 140. 
Thenard, his experiments on yeast, 

313. 
Thermometers , scales of, 418. 
Tin, action on nitric acid, 292. 
Tobacco, juice contains ammonia, 
94. 

Leaves of, 345. 



YIN 



429 



woo 



Tobacco, value of, proportional to 
quantity of potash in the soil, 

Nitric acid in, 97. 

In Virginia, 151. 
Transfurmutioii, by heat, 306. 

Chemical, 71,21)1. 

Chemical transformations differ 
from decompositions, 71, 

Of acetic acid, 306. 

Of arragonite, 298. 

Of carbonic acid, 142. 

Of meconic acid, 306. 

Not affected by the vital princi- 
ple, 74. 

Explained, 74. 

Of bodies containing nitrogen, 
305. 

Of bodies destitute of nitrogen, 
305. 

Results of, 75. 

Of sugar, 303. 

Of wood, 306. 

Of cyanic acid, 311. 

Of cyanogen, 31 1. 

Of gluten, 339. 
Transplantation, effect of, 132. 
Trees, diseases of, 137. 

Require alkalies, 154. 

Ulmin, 30. 

Urea, 70, 87 ; converted into car- 
bonate of ammonia, 97. 

In urine, 189. 
Uric Acid, yields ammonia, 192. 

Transformations of, 193. 
Urinary calculi, treatment of, 74. 

Organs, eliminate nitrogen, 73. 
Urine, contains nitrogen, 97. 

Its use as a manure, 95, 201, 211. 

Of men, &c., 190. 

Of horses, 202. 

Human, analysis of, 190. 

Of cows, 202. 

Its use in China and Flanders, 
95, 194. 

Of swine, 202. 

Vaccination, its effect, 405. 

Vegetable Albumen, 96. 

Life, one end of, 23. 

Mould, 363. 

Juices, fermentation of, 314. 
Vesuvius, fertile soil of, 149. 
Vines, new mode of manuring, 253. 

Juice of, yields ammonia, 94. 
Vinous Fermentation, 338. 



Virginia, early products of its soUa, 

151. 
Virus, of small pox, 405. 

Vaccine, 405. 
Vitality, what, .59. 
Vital Principle, 73. 

Value of the term, 75. 

How balanced in the blood, 374. 
Vital Processes of plants, 1 66. 
Voelckel, his analysis of guano, 96. 

Water, carbonic acid of, ab- 
sorbed, 44. 
Composition of, 81. 
Dissolves mould, 364. 
Freezing of, 296. • 

Plants, their action upon, 56. 
Rain, contains ammonia, 91. 

required by plants, 28. 

required by gypsum, 102. 

Hard, made soft, 92. 

Salt, analysis of, 124. 
IVavellite, 156. 
West Indies, soil of, 244. 
Wheat, analysis of, 154. 

Ashes of, used as a manure, 213. 

Exhausts, 152. 

Nitrated, 272. 

Gluten of, 94. 

Manure for, 213. 

Why it does not thrive on cer- 
tain soils, 153. 

In Virginia, 151. 
Wilbrand, Dr., on maple sugar, 93. 
Willoics, growth of, 133. 
Wine, effect of gluten upon, 347. 

Fermentation of. 347. 

Properties of, 347. 

Substances in, 341. 

Taste and smell, 342. 

Varieties of, 342. 
Wood, decomposition of, 320. 
Wiihler, his analysis of limestone, 

153. 
Wood charcoal, may replace hu- 
mus, 78. 

a manure, 249. 

Decayed combustion of, 362. 

Absorbs ammonia, 104. 

Analysis of, 52. 

Bread from, 133. 

Composition of, 264. 

Conversion of, into humus, 335. 

Decay of, 357. 

Requires air, 358. 

Decomposition of, 320. 

Elements of, 358, 360. 



WOR 



430 



ZIN 



Wood, transformation of, 306. 

Effect of moisture and air on, 
358. 

Formation of, 138. 

Source of its carbon, 39. 
Wood Coal, how produced, 365. 

Analysis of, 367, 368. 
Woody Fibre, changes in, 358. 

Composition of, 358. 

Decomposition of, 358. 

Formation of, 48. 

Moist, evolves carbonic acid, 358. 

Mould from, 364. 
Wormioood, effect of its culture, 
120. 



Wort, fermentation of, 350. 
Wounds, effect of putrefying sub- 
stances on, 386. 

Yeast, 315. 

Destroyed, 341. 
Experiments on, 316. 
Formed, 340. 
Its mode of action, 318. 
Its production, 315. 
Two kinds of, 350. 

ZeiNE, 98. 

Zinc, decomposition of water with, 



